Centered or not centered?

I am not a designer but I am trying to learn some basic principles of 开发者_如何转开发web-design. A basic question I am wondering about is whether or not to center a page's content on the screen. Maybe you are familiar with A List Apart. They provide a good number of articles on web-design. What strikes me as odd is their own design. The whole page is to the left of my 24 inch screen (about 11 inch to the right is completely blank). What are the pros and cons of centered vs not centered?

Thanks in advance!

An average user of an all-purpose web site is likely to have 1280*1024+ resolution. If you also support 1024*768 (i.e. max 960px width) and put your content to the left side of the screen, users at 1280*1024 would just have to turn their head a little bit but think of a user at 1920*1080, who would need to actually change seating position to clearly read the content, which would be occupying just the left half of the screen.

Apart from those, I don't see any technical advantage or disadvantage of floating to the left.

People read left justified text faster than centered text.

A List Apart has a content column that's a bit wide for comfortable reading on a large screen. It's probably the correct size for a smart phone. People are more comfortable reading columns of text, like a newspaper, than if the text runs across the screen.

If you want to center the entire layout, you can, but it's easier for people to size their browser to fit a left justified layout. Some people may have 3 or 4 browser windows showing on their wide screens at the same time. I have two monitors on my work and home computer, and sometimes I'll have 3 browser windows showing at the same time.