A couple of weeks ago, I talked about feature detection and browser detection. That post featured a little bit about user-agent sniffing and the comments continued the trend. I maintain that user-agent sniffing is an important technique to keep in your back pocket for those rare occasions when it’s needed. Before being able to do that, though, it’s useful to understand why user-agent string detection is considered to be such an inexact science. And to do that, you need to take a look at how the user-agent string has evolved over the years.

The absence of a DOCTYPE is a crime punishable by death. You may have relied on the following DOCTYPE in the past, but it's important to know that this is now being superceded by a leaner and meaner snippet.

In writing POSH HTML we should use the most suitable or semantically accurate element. In HTML4 <div> is a general block-level container element; it doesn’t have any semantic meaning beyond being block-level, and is used when there are no more appropriate elements (i.e. all the time). There is no requirement for the things inside the <div> to be related to each other.

Airbnb has a brilliantly engineered title, and with a little bit of effort, they optimize the search experience for 2 major types of search engine users:

(Confused? Read Detecting HTML5 Features for a conceptual introduction. Want an all-in-one library instead? Try Modernizr.)

Great introduction to html and css for newcomers.

This page contains the 252 allowed entities in HTML 4 and XHTML 1.0, as outlined in section 24 of the official HTML 4 specifications, published by the W3C. If you're new to this site, you can find help on how to use this reference.

Lightbox using pure HTML and CSS, no Javascript required. Add Webkit transitions?

Create quick HTML forms

Not super helpful, but maybe a last ditch resource. Basically a huge list of various glossaries.