Support web standards! Happy Blue Beanie Day! Read more information about it here: Blue Beanie Day 2011
The gist of it is best explained by Alyssa Walker:
It’s these people you can thank for building Internet experiences focused on usability, meaning those of you puttering along on the oldest copy of Internet Explorer can navigate sites just as beautifully as the newest Google Chrome browser.
Web standards are the backbone of user experience. Think it’s easy to build a website? Give it a go and look at it across multiple browsers ( Internet Explorer, Safari, Chrome, Firefox, Opera). Lack of support for certain features among different browsers leads to different looks and functionality across them. This is why you pay professional web developers; we know how to make a website look and work the same across the board. Web standards help us use universal techniques to design a web experience that is the same no matter what browser or device you use.