E-commerce glossary
Thirty-five short definitions, written for a merchant reading a quote, an audit report or a message from a supplier and stumbling on a word. Each page says what the term means, where it shows up on a real shop, and what happens when that thing goes wrong.
Who this glossary is for
People rarely land here out of curiosity. They land here because a quote mentions an override, because a host talks about TTFB, because an audit complains about a missing canonical tag, or because a developer answered "it's the cache" without saying which one. Technical vocabulary is not decorative: while it stays vague, there is no way to tell whether what is being proposed answers the problem.
These definitions assume nothing and try to impress no one. They stay deliberately short: the point is to understand a word in a minute and go back to the conversation you were having, not to sit through a computing course.
How the glossary is organised
The thirty-three entries are listed alphabetically, but they fall into five natural families. Shop vocabulary: back office and front office, slug, permalink, checkout funnel, variation, product attribute, module. Server and data vocabulary: DNS, SSL/TLS, CDN, FTP/SFTP, cron, database and index, SQL query, serialisation, webhook, REST API.
Then performance: cache, TTFB, LCP, Core Web Vitals. Search: canonical, hreflang, sitemap, robots.txt, 301 redirect, migration. And finally development and diagnosis: 500 error, debug mode, hook, override, child theme, payment gateway. If you don't know which family to look in, start from the word you read: each definition links to the neighbouring terms it relies on.
Why this vocabulary matters when you talk to a supplier
One example makes the case. "Clear the cache" means nothing until you say which one: a shop commonly stacks four — the platform's application cache, PHP's opcode cache, a module or intermediate server cache, and the visitor's browser cache. Clearing the first touches none of the other three. A great many "my change isn't showing" reports come from exactly that confusion, and one precise question settles the discussion.
The same goes for module, extension and plugin, which name the same idea on three different platforms, or for override, which on PrestaShop means a specific file under override/ and not any change to the code. Knowing what a word covers lets you ask the deciding question: does the proposed work touch the core, the theme or a module, and what happens at the next update.
An understandable quote is not a simplified quote: it is one whose every line you can check. That is what this glossary is for.
Four definitions to read first
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Cache
The different cache layers on a shop, what each one stores, and which to clear for a given symptom.
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Hook
The attachment point that lets a module add behaviour without changing the platform core.
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Override
Overriding a core class: what it allows, what it breaks, and why two modules can fight over one.
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301 redirect
The permanent redirect, the basic tool of any rebuild or migration that doesn't want to lose its rankings.
In this section
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Hook
A hook is a specific point in PrestaShop's code where a module can run its own logic, without touching the core files.
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Override
An override is a file placed in PrestaShop's override/ folder that replaces the behaviour of a core class, without modifying the…
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Module
A module is an installable PrestaShop extension that adds or changes a store feature by hooking into hooks, without ever…
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Child theme
A child theme is a WordPress theme that inherits the appearance and functionality of a parent theme, while only overriding the…
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Cache
A cache is a temporary copy of an already-computed result, kept so it doesn't have to be recalculated on every visit.
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CDN
A CDN, or content delivery network, is a set of geographically distributed servers that serve a site's static files from the…
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TTFB
TTFB, or Time To First Byte, measures the delay between the browser sending a request and receiving the first byte of the…
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Core Web Vitals
Core Web Vitals are a set of metrics defined by Google to measure a page's real-world experience as perceived by a visitor…
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LCP
LCP, Largest Contentful Paint, measures the time needed to display the largest visible element of a page on screen.
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Canonical
The canonical tag, inserted in a page's via link rel="canonical", tells search engines which URL should be treated as the…
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Hreflang
The hreflang tag, inserted in a page's or declared in a sitemap, tells search engines which language or regional version of a…
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Sitemap
A sitemap is an XML file listing the pages of a site that its owners want search engines to crawl, sometimes with indications of…
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Robots.txt
The robots.txt file is a text file placed at the root of a site that tells crawlers (Googlebot, Bingbot…) which areas they're…
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301 redirect
A 301 redirect is an HTTP response that indicates a resource has permanently moved to a new URL, passing on to that new address…
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500 error
A 500 error, or "Internal Server Error", is a generic HTTP status code returned by the server when it hits a problem that stops…
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Debug mode
Debug mode is a setting that replaces the generic error messages shown to visitors with the full technical detail: the file…
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Back office and front office
An online shop has two faces: the front office, which visitors see, and the back office, where the merchant works. Neither term…
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Checkout
The checkout (or checkout process) refers to the multi-step journey a customer follows between confirming their cart and…
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Payment gateway
A payment gateway is the intermediary service that handles the bank transaction between the merchant site and the customer's…
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Webhook
A webhook is an automatic HTTP request, usually a POST, that a third-party service sends to a URL on the merchant site when a…
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REST API
A REST API is an interface that lets two computer systems exchange data over HTTP, using standard verbs (GET, POST, PUT, DELETE)…
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Cron
A cron job is a process scheduled to run automatically at regular intervals, without human intervention.
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SSL/TLS
SSL/TLS is the encryption protocol that secures the connection between a visitor's browser and the server hosting the site…
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DNS
DNS (Domain Name System) is the system that translates a domain name into an IP address, so the browser knows which server to…
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FTP / SFTP
FTP and SFTP are two protocols for transferring files between a computer and a web server; SFTP encrypts the connection, unlike…
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Database and index
A database is the system that stores and organises, in tables, all the information behind a shop: products, orders, customers and…
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SQL query
An SQL query is an instruction written in SQL (Structured Query Language) sent to a database to read, add, change or delete…
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Migration
A migration means transferring an online store from one version, platform or host to another, while keeping all of its data…
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Serialisation
Serialisation is the process that turns a complex data structure (array, object) into a storable text string, with the ability to…
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Permalink
A permalink is the final, permanent URL of a WordPress piece of content: a post, a page or, with WooCommerce, a product page.
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Slug
A slug is the readable part of a URL that identifies a page, article or product, usually derived automatically from its title.
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Product attribute
A product attribute is a characteristic that varies between versions of an item, such as colour or size, and that's used to…
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Product combination
A combination, also called a variation, is a specific version of a product resulting from a cross of its attributes, for example…
Frequently asked questions
Do these definitions apply to both PrestaShop and WooCommerce?
Do I need this vocabulary to run my shop?
Are the definitions enough to do the work myself?
Why are the definitions so short?
Describe your need in one minute
A few targeted questions so I can reply with an estimate rather than another questionnaire.