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Glossary

Each term starts with a short definition, followed by an explanation, examples and, where it helps, what it means for a WordPress site.

A

  • Anchor text

    SEO and marketing

    Anchor text is the clickable text of a hyperlink, the words a visitor sees and clicks on. It tells both readers and search engines…

  • Apache HTTP Server

    Web hosting

    Apache HTTP Server, usually just called Apache, is a free, open-source web server developed by the Apache Software Foundation. It receives browser requests, serves…

B

  • Backdoor

    Web security

    A backdoor is hidden access, built into software or installed after an intrusion, that lets someone get back into a system while bypassing normal…

  • Backlink

    SEO and marketing

    A backlink (inbound link) is a link on another website that points to a page on yours. Search engines use backlinks to discover pages…

  • bcrypt hashing

    Web security

    bcrypt is a hashing function designed for storing passwords. It builds in a random salt and an adjustable cost factor that makes each computation…

  • Brute-force attack

    Web security

    A brute-force attack consists of automatically trying a very large number of passwords, or username and password pairs, until one of them unlocks an…

C

  • Canonical URL

    SEO and marketing

    The canonical URL is the address a search engine keeps as the reference version when the same content is available at several URLs. Site…

  • CDN

    Web hosting

    A CDN (content delivery network) is a set of servers spread around the world that keep cached copies of a website's files and serve…

  • Clickjacking

    Web security

    Clickjacking means displaying a legitimate site in an invisible frame layered over a booby-trapped page: the victim thinks they are clicking a harmless button…

  • Cloud hosting

    Web hosting

    Cloud hosting refers to computing resources (virtual servers, storage, databases, platforms) provided on demand from a provider's shared infrastructure, adjustable quickly and billed by…

  • CloudLinux and CageFS

    Web hosting

    CloudLinux is a Linux operating system built for shared hosting. With LVE, it caps each account's resources (CPU, memory, disk I/O, processes); with CageFS,…

  • Content Security Policy (CSP)

    Web security

    Content Security Policy (CSP) is an HTTP header through which a site tells the browser which sources of scripts, styles, images or frames it…

  • Core Web Vitals

    SEO and marketing

    Core Web Vitals are three metrics defined by Google to measure real visitors' experience: LCP for loading speed, INP for responsiveness to interactions and…

  • cPanel

    Web hosting

    cPanel is a web hosting control panel for Linux servers, used by many shared hosting providers. Paired with WHM, the server administrator's interface, it…

  • Crawl budget

    SEO and marketing

    Crawl budget is the set of URLs a search engine like Google can and wants to crawl on a website. It depends on how…

  • Credential stuffing

    Web security

    Credential stuffing is an automated attack that replays, on one site, username and password pairs stolen in data breaches at other services. It succeeds…

  • Cron (and WP-Cron)

    Web hosting

    Cron is the job scheduler of Unix and Linux systems: it runs commands at set times based on a table called a crontab. WP-Cron…

  • CSRF (cross-site request forgery)

    Web security

    CSRF (cross-site request forgery) is an attack that makes a logged-in user's browser send a request, without their knowledge, to a site where their…

  • CVE

    Web security

    A CVE (Common Vulnerabilities and Exposures) is a unique public identifier, in the form CVE-2024-4577, assigned to a disclosed security vulnerability. This catalog, sponsored…

  • CVSS score

    Web security

    The CVSS score (Common Vulnerability Scoring System) is a rating from 0 to 10 that measures the technical severity of a vulnerability, based on…

D

  • DDoS attack

    Web security

    A DDoS (distributed denial-of-service) attack tries to make a website or server unavailable by flooding it with traffic or requests sent from a large…

  • Dedicated server

    Web hosting

    A dedicated server is a physical machine rented to a single customer, who gets all of its processors, memory and drives, with full administrator…

  • DirectAdmin

    Web hosting

    DirectAdmin is a web hosting control panel for Linux servers, known for being lightweight, that organizes access into three levels: admin, reseller and user.…

  • DNS

    Web hosting

    DNS (Domain Name System) is the internet's distributed directory: it translates a domain name such as example.com into an IP address and provides other…

  • Duplicate content

    SEO and marketing

    Duplicate content is identical or very similar content available at several URLs, on the same site or across different sites. Google groups these duplicates…

E

  • E-E-A-T

    SEO and marketing

    E-E-A-T stands for the Experience, Expertise, Authoritativeness and Trustworthiness of a piece of content and its author. This framework, described in Google's Search Quality…

F

  • Featured snippet (position zero)

    SEO and marketing

    A featured snippet, often called position zero, is the highlighted excerpt Google sometimes shows above the regular results: a passage from a page displayed…

  • File inclusion (LFI / RFI)

    Web security

    File inclusion is a PHP vulnerability in which an attacker controls the path passed to include or require. With LFI (local file inclusion), they…

  • Fingerprinting

    Web security

    Fingerprinting means identifying the software that runs a website, its version and its components from visible clues: HTTP headers, the generator tag, file paths,…

G

  • GEO (Generative Engine Optimization)

    SEO and marketing

    GEO (Generative Engine Optimization) covers the practices that aim to make content visible and cited in the answers of generative engines: Google's AI Overviews…

H

  • Heading tags (H1 to H6)

    SEO and marketing

    Heading tags (H1 to H6) are the HTML elements that define the headings and subheadings of a page, from the most important (H1) to…

  • Honeypot

    Web security

    A honeypot is a decoy deliberately set up to attract attackers: a fake server, a nonexistent web address or a hidden form field. Since…

  • Hotlinking

    Web hosting

    Hotlinking (or direct linking) means displaying on one site an image, video or file hosted on another site, by pointing straight to its URL…

  • Hreflang

    SEO and marketing

    Hreflang is an HTML attribute that tells search engines about the different language or regional versions of the same page. It lets Google show…

  • HSTS

    Web security

    HSTS (HTTP Strict Transport Security) is an HTTP header that tells the browser to contact a site only over HTTPS for a set period…

  • htaccess file (.htaccess)

    Web hosting

    The .htaccess file is a configuration file read by the Apache web server, and by LiteSpeed, in the directory where it sits and in…

  • HTTP security headers

    Web security

    HTTP security headers are instructions the server sends with every page and the browser enforces: forcing HTTPS, forbidding display in an external frame, limiting…

  • HTTP/2 and HTTP/3

    Web hosting

    HTTP/2 and HTTP/3 are the recent versions of the web's protocol. HTTP/2 carries many requests in parallel over a single TCP connection, as binary…

I

  • IDOR (insecure direct object reference)

    Web security

    An IDOR (insecure direct object reference) vulnerability lets someone access another user's data simply by changing an identifier in a request, such as an…

  • IIS (Windows Server)

    Web hosting

    IIS (Internet Information Services) is Microsoft's web server, built into Windows Server and Windows. It runs PHP through its FastCGI module and php-cgi.exe, and…

  • Indexing

    SEO and marketing

    Indexing is the stage where a search engine analyzes a page it has crawled, then stores it in its index, the database it draws…

  • Inodes

    Web hosting

    An inode is the structure that describes a file or directory on a Unix or Linux file system: type, permissions, owner, size, timestamps and…

  • Insecure deserialization

    Web security

    Insecure deserialization is a vulnerability that occurs when an application rebuilds objects from attacker-controlled data, for example with unserialize() in PHP. The methods triggered…

  • Internal linking

    SEO and marketing

    Internal linking is the set of links that connect the pages of the same website to one another. It helps search engines discover every…

L

  • Let's Encrypt

    Web hosting

    Let's Encrypt is a free, automated certificate authority run by the nonprofit ISRG. It issues TLS certificates that validate control of a domain through…

  • Link building

    SEO and marketing

    Link building is the set of actions aimed at getting other websites to link to yours, in order to improve its visibility and popularity…

  • LiteSpeed Web Server

    Web hosting

    LiteSpeed Web Server (LSWS) is a commercial, event-driven web server designed as a drop-in replacement for Apache: it reads Apache's configuration and .htaccess files.…

  • llms.txt

    SEO and marketing

    llms.txt is a proposed Markdown file placed at the root of a website to present its content to large language models: a title, a…

  • Long tail

    SEO and marketing

    The long tail is the set of long, specific search queries that are each searched rarely but together make up a large share of…

M

  • Malware

    Web security

    Malware (malicious software) is a program or piece of code introduced into a system to harm its owner or users: stealing data, taking control,…

  • Managed hosting

    Web hosting

    Managed hosting means entrusting all or part of the management of an IT system to an outside provider: server administration, updates, monitoring, backups or…

  • Meta description

    SEO and marketing

    The meta description is an HTML tag that sums up a page's content in one or two sentences. Invisible on the page itself, it…

  • MySQL and MariaDB

    Web hosting

    MySQL and MariaDB are two relational database management systems, using the SQL language, where WordPress stores posts, pages, settings, accounts and orders. MariaDB started…

N

  • Nginx

    Web hosting

    Nginx (pronounced “engine-x”) is an open source, event-driven web server that also works as a reverse proxy, load balancer and HTTP cache. Light on…

  • nginx.conf

    Web hosting

    nginx.conf is the main configuration file of the Nginx web server. It's organized in nested blocks called contexts (events, http, server, location) that describe…

  • Nofollow attribute

    SEO and marketing

    The nofollow attribute is a value of an HTML link's rel attribute (rel="nofollow") that tells search engines the site does not vouch for the…

  • Nonce

    Web security

    A nonce is a value, in principle random and used only once, added to an exchange to prevent it from being replayed or forged.…

O

  • OPcache

    Web hosting

    OPcache is the PHP extension that keeps already compiled script code (the opcodes) in shared memory. PHP no longer needs to read and parse…

  • OpenLiteSpeed

    Web hosting

    OpenLiteSpeed (OLS) is the open source edition, under the GPLv3 license, of the LiteSpeed web server. Event-driven and equipped with a built-in page cache…

P

  • Password salting

    Web security

    Password salting means adding a unique random value, the salt, to each password before computing its hash. Two identical passwords then produce different hashes,…

  • Phishing

    Web security

    Phishing is a scam technique that imitates a message from a trusted organization (bank, hosting provider, government agency, online service) to get the victim…

  • PHP-FPM

    Web hosting

    PHP-FPM (FastCGI Process Manager) is PHP's official FastCGI process manager. It runs groups of PHP processes, called pools, that receive the scripts passed on…

  • Plesk

    Web hosting

    Plesk is a web hosting control panel that runs on Linux and Windows Server. It lets you manage a server and its sites from…

  • Privilege escalation

    Web security

    Privilege escalation is an attack that grants more rights than were originally given: a visitor becomes an administrator, a subscriber changes settings, a customer…

R

  • Rank tracking

    SEO and marketing

    Rank tracking means regularly measuring where a website's pages rank in search engine results for a list of queries. It relies on Search Console,…

  • Ransomware

    Web security

    Ransomware is malicious software that locks access to a system or encrypts its data, then demands a ransom to restore it. Attackers often copy…

  • Redis and Memcached (object cache)

    Web hosting

    Redis and Memcached are in-memory data stores that WordPress uses as a persistent object cache. They keep the results of database queries and other…

  • Remote code execution (RCE)

    Web security

    Remote code execution (RCE) is a vulnerability that lets an attacker make a server run their own instructions over the network, without any legitimate…

  • Robots.txt

    SEO and marketing

    Robots.txt is a text file placed at the root of a website that tells crawlers which URLs they may or may not crawl. It…

S

  • SEA (search engine advertising)

    SEO and marketing

    SEA (search engine advertising), also called paid search or PPC, means advertising on search engines: the advertiser pays to show ads on results pages,…

  • Search intent

    SEO and marketing

    Search intent is the real need behind a query: getting information, completing an action or purchase, reaching a specific website or finding a place.…

  • SEO (search engine optimization)

    SEO and marketing

    SEO (search engine optimization) is the set of techniques that improve a website's visibility in the unpaid, organic results of search engines. It works…

  • SERP

    SEO and marketing

    The SERP (search engine results page) is the page a search engine displays after a query. It mixes organic results, paid ads and special…

  • Shared hosting

    Web hosting

    Shared hosting is a setup where many websites, owned by different customers, share the same server and its resources: CPU, memory, disk and software.…

  • SQL injection

    Web security

    SQL injection is an attack that slips fragments of SQL code into data sent to a website in order to hijack the query the…

  • SSH and SFTP

    Web hosting

    SSH (Secure Shell) is a protocol that opens an encrypted session on a remote server so you can type commands there. SFTP (SSH File…

  • SSRF (server-side request forgery)

    Web security

    An SSRF (server-side request forgery) vulnerability lets an attacker make the server send requests to an address of their choosing: internal services, the cloud…

  • Staging environment

    Web hosting

    A staging environment is a private copy of a live website, on the same kind of server, used to test updates, new plugins, theme…

  • Structured data

    SEO and marketing

    Structured data is standardized markup, most often in JSON-LD format with the schema.org vocabulary, that explicitly describes a page's content: article, product, recipe, organization…

  • Supply chain attack

    Web security

    A supply chain attack compromises a software vendor, a dependency or an update channel in order to reach that vendor's customers. The malicious code…

T

  • Title tag

    SEO and marketing

    The title tag is the HTML element that gives a web page its title. Shown in the browser tab, it is also the main…

  • TLS / SSL

    Web security

    TLS (Transport Layer Security) is the protocol that encrypts traffic between a browser and a server, guarantees its integrity and authenticates the server through…

  • TLS certificate

    Web security

    A TLS certificate is an electronic file that binds a domain name to a public key, signed by a certificate authority that browsers trust.…

  • Topic cluster (semantic cocoon)

    SEO and marketing

    A topic cluster is a way of organizing content and internal links around a subject: a pillar page, cluster pages and supporting pages linked…

  • TTL (DNS)

    Web hosting

    The TTL (Time To Live) of a DNS record is the number of seconds a resolver may keep the answer in its cache before…

  • Two-factor authentication (2FA)

    Web security

    Two-factor authentication (2FA) adds a second proof of identity to the password at login: a temporary code generated by an app, a security key…

U

  • Uptime and SLA

    Web hosting

    Uptime is the time during which a service, such as a website or a server, is available, expressed as a percentage of a period.…

  • User enumeration

    Web security

    User enumeration is a reconnaissance technique that builds a list of a site's valid usernames by exploiting its responses: error messages, author URLs, public…

V

  • Virtual patching

    Web security

    Virtual patching is a filtering rule that blocks the exploitation of a specific vulnerability without changing the code of the affected software. Applied by…

  • VPS (virtual private server)

    Web hosting

    A VPS (virtual private server) is a virtual machine created on a shared physical server, with its own operating system, reserved resources and full…

W

  • WAF (web application firewall)

    Web security

    A WAF (web application firewall) is a filter placed in front of a web application that inspects every HTTP request (URL, parameters, headers, body)…

  • WP-CLI

    Web hosting

    WP-CLI is the official command-line interface for WordPress. From a terminal, often over SSH, it can do almost everything the admin area offers, and…

X

  • XML sitemap

    SEO and marketing

    An XML sitemap is a file listing the URLs of a website that you want crawled, sometimes with their last modification date. It helps…

  • XML-RPC

    Web security

    XML-RPC is a protocol for calling functions remotely through XML messages. In WordPress, the xmlrpc.php file lets you publish from an external application and…

  • XSS (cross-site scripting)

    Web security

    XSS (cross-site scripting) is a vulnerability that lets an attacker run their own JavaScript in the page another visitor is viewing. The script then…

Z

  • Zero-day vulnerability

    Web security

    A zero-day vulnerability is a security flaw exploited by attackers before the software vendor has fixed it, and often before the vendor even knows…

#

  • 3-2-1 backup rule

    Web hosting

    The 3-2-1 backup rule means keeping three copies of your data (the original and two backups), on two different types of media, with one…

  • 301 redirect

    SEO and marketing

    A 301 redirect is an HTTP response telling browsers and search engines that a URL has moved permanently to another one. Visitors land on…

  • 404 error

    SEO and marketing

    A 404 error (Not Found) is the HTTP status code returned when the requested URL doesn't match any resource on the server: a deleted…

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