These are my oft-answered responses to Frequently Asked Questions in the various Usenet newsgroups that I read. It seems simpler to refer a questioner here, rather than looking up stuff to repost over and over.
One of the most frequently-asked questions is "What is the most common screen resolution, so I can size my web pages?" Screen resolution has no bearing whatsoever on the answer.
Since you, the web page author, have no idea how wide, or how narrow, my browser window is at any given moment, you should consider not using a fixed-width size for your pages. My screen is 1680×1050; should you make your page for that? No, because my browser window is usually about half that width. But not always.
So there are two accurate answers to "Which resolution should I design for?":
- All of them
- None of them
You also need to know that nearly all modern browsers allow the user to change the font size. If you set up sections of your page using fixed measurements, and I need to up the size because you used microfonts, all your text is going to fall out of your carefully planned layout. As a general rule, use percentages or em units for nearly all measurements except borders and the sizes of images.