99creatix Book a 15-minute fit call
Glossary · Web design & Shopify

CMS

Also called content management system

Reviewed 31 Oct 2026 By Madiha Fatima 4 min read Check it yourself: yes, free

4 min
Definition

A CMS, or content management system, is the software behind a website that lets you add and edit pages, posts, images and products through a login screen instead of editing code. WordPress, Shopify, Squarespace and Wix are all content management systems. The CMS decides how easy the site is to change, move and own.

The choice matters less for ranking than people are told. Google ranks pages, not platforms, and a well-built site on any mainstream CMS can rank. It matters a great deal for cost and control: who can edit it, what the hosting costs, whether you can take it elsewhere and whether anyone other than the agency that built it can work on it.

Short version: the editing system behind the site, and the thing that decides who can change it.
Why it matters for your business

"Custom CMS" in a quote
usually means only they can touch it.

The CMS is the line in a web design quote that decides the next five years. A site on WordPress or Shopify can be edited by you, moved to another host and handed to any other developer. A site on an agency's own custom CMS can usually be edited only by them, hosted only by them and, when you leave, rebuilt from nothing. The quote may be cheaper. The exit is not.

It also sets your running costs. A hosted CMS like Shopify or Squarespace bundles hosting, security and updates into one monthly fee. WordPress is free software but needs hosting, updates and a care plan, which is what a maintenance retainer is usually paying for. Neither is wrong. The wrong thing is not knowing which you are buying.

For search the CMS is mostly neutral, with two caveats. It must let you edit titles, descriptions and slugs on every page, and it must produce pages that load quickly on a phone. Some page builders and some proprietary systems fail the second test badly.

Example

Two quotes for the same law firm website,
one line apart.

Quote A

A firm of solicitors received a quote for a new site built on the agency's own platform. Lower price, hosting included, updates included. The CMS line read: proprietary content management system, fully managed.

Platform: agency's own CMS Hosting: agency only Editing: by request, billed Leaving: start again
Quote B

The second quote was higher and built on WordPress with a standard theme. Hosting was the firm's own account, the login was theirs and any developer could take it on. Two years later the firm wanted to change agencies. With Quote B that is a handover of a login. With Quote A it would have been a second new website. The first quote was not cheaper. It had only moved the cost to the day they wanted to leave.

How to check it on your site

Four questions, answered by your own login.

Tick each one as you go. 0 of 4 checked on your site.

  1. Find out what your site runs on

    Try adding /wp-admin to your web address: a login page means WordPress. A Shopify store shows Powered by Shopify in the footer or has a /admin login. Otherwise, ask whoever built it to name the CMS in writing. If they say custom or proprietary, ask the next three questions.

  2. Confirm you hold the keys

    You should have an administrator login to the CMS, the hosting account and the domain registrar, in your name, not the agency's. If any of the three is missing, ask for it now, while the relationship is good.

  3. Try to edit a page yourself

    Log in and change a sentence on an inner page. If you can, the CMS is doing its job. If the agency has to do it, find out whether that is a setting they can change or a limit of the platform.

  4. Ask what leaving looks like

    Ask, in writing: if we move to another developer or host, what do we take with us? The right answer for a mainstream CMS is everything, as an export or a copy. If the answer is the content but not the site, the site was never really yours.

Related terms

Usually in the same sentence.

Read next

Where this shows up in practice.

Pricing & transparency How to evaluate a website quote

The platform line is one of the few that decide whether a quote is a good one.

 Pricing & transparency The fees agencies hide

Proprietary platforms and locked hosting are two of them.

 Pricing & transparency Agency vs freelancer vs DIY website

Which CMS each route usually gives you, and what that means later.
Related service

Every site from web design and development is built on WordPress or Shopify, on hosting and logins in your name, so you can leave whenever you like. Prices are on the price list, not on a call.

See the web design service
Reviewed by Madiha Fatima, founder of 99creatix

Every entry in this glossary is written and checked by the person who runs the agency, reviewed at least once a quarter and dated. Last reviewed 31 October 2026.

Spotted an error or a term we are missing? Tell us and it is fixed within the week.

Did this explain it?
Next step

Not sure what your site runs on,
or who really owns it?

Fifteen minutes and whatever logins you have. We will tell you what the site is built on, what you would take with you if you left and what any change would cost, before you decide anything.

Book a 15-minute fit call Back to the glossary