LiquidPurple - Strategic Website Management
Liquid Purple Liquid Purple

Glossary of Terms

We have compiled this list of terms and definitions to help you better understand the terminology used within the web development community.

Document Type

Search for glossary terms (regular expression allowed)
Document Type declaration tells the browser which version of HTML your page uses. Getting it right ensures browsers render your page in standards mode instead of falling back to quirky legacy behavior. It is a small detail that prevents big layout and compatibility headaches.

Document Type

The document type declaration — that <!DOCTYPE html> line at the very top of your page — tells the browser which version of HTML your page is written in. It is one line of code, it takes one second to add, and skipping it can cause hours of debugging. Without it, browsers fall back to "quirks mode," rendering your page with all kinds of legacy weirdness.

Why It Matters

  • It controls how browsers render your page. With a proper doctype, browsers use standards mode — consistent, predictable rendering across platforms. Without it, you get quirks mode, where box sizing, margins, and layout rules change unpredictably.
  • CSS behaves differently in quirks mode. Things like box-sizing, table widths, and inline element spacing follow legacy rules in quirks mode. Your carefully written CSS may produce completely different results.
  • It affects cross-browser consistency. Standards mode ensures all modern browsers follow the same rules. Quirks mode triggers browser-specific legacy behaviors that vary wildly, making consistent design nearly impossible.
  • Validators require it. HTML validators check for a valid doctype. Without one, your page fails basic validation checks, which can affect accessibility compliance and professional credibility.

How to Get It Right

  1. Use the HTML5 doctype. Put <!DOCTYPE html> as the very first line of every HTML page. It is case-insensitive, short, simple, and universally supported.
  2. Make it the first thing in the document. Nothing should come before the doctype — not even whitespace or comments. Anything before it in some browsers can trigger quirks mode.
  3. Do not use old-style doctypes. Earlier HTML versions had long, complicated doctypes referencing DTD files. The HTML5 doctype replaced all of them. There is no reason to use <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"...> anymore.
  4. Check every template and page. Content management systems, email templates, and dynamically generated pages sometimes miss the doctype. Audit all your templates to make sure every page starts with one.
  5. Verify rendering mode in dev tools. Open your browser's developer tools and check whether the page is rendering in standards mode or quirks mode. The document properties panel will tell you.

Common Mistakes

  • Forgetting the doctype entirely. Some pages, especially those generated by older systems or built in a hurry, simply do not have a doctype. The browser defaults to quirks mode and things look subtly wrong.
  • Putting a BOM or whitespace before it. A byte order mark (BOM) or blank lines before the doctype can trigger quirks mode in some browsers. Keep the doctype on the absolute first line.
  • Using an XHTML doctype for an HTML page. XHTML doctypes have strict parsing rules. If your page is not valid XHTML (and most are not), using an XHTML doctype can cause rendering failures.
  • Assuming the doctype only matters for old browsers. Modern browsers still check the doctype to determine rendering mode. It is not a relic — it is an active part of how every browser processes your page.
Bottom Line: Put <!DOCTYPE html> on the very first line of every HTML page. It takes one second, costs nothing, and prevents quirks mode from silently breaking your layout and styles.
Hits - 236
Synonyms: DOCTYPE, HTML Declaration

What Does "Liquid Purple" mean?

noun | / LIK-wid PUR-pul /

  1. (biochemistry) Also known as visual purple or rhodopsin — a light-sensitive receptor protein found in the rods of the retina. It enables vision in dim light by transforming invisible darkness into visible form. Derived from the Greek rhódon (rose) and ópsis (sight), its name reflects its delicate pink hue and vital role in perception.

  2. (modern usage) Liquid Purple — a digital marketing agency specializing in uncovering unseen opportunities and illuminating brands hidden in the digital dark. Much like its biological namesake, Liquid Purple transforms faint signals into clear visibility — revealing what others overlook and bringing businesses into the light.

Origin: From the scientific term rhodopsin, discovered by Franz Christian Boll in 1876; adopted metaphorically by a marketing firm dedicated to visual clarity in the age of algorithms.

Client Login

Copyright © 2026 Liquid Purple | All Rights Reserved.
Follow us around the web:
 

Rooted in Southern California, Serving the World.
For over 20 years, Liquid Purple has been headquartered in the heart of Southern California, serving clients across Irvine, Newport Beach, Anaheim, and the greater Los Angeles area. While we are proud of our local roots, our digital reach extends far beyond our local area. We support businesses in major hubs like Denver, Dallas, New York, and Miami, as well as international clients. Our ability to operate across time zones means you can often wake up to completed tasks and progress updates—keeping your business moving while you sleep.