What text size should you use?
Back then, in 90′, Verdana, 11 pixel is all that we love. We love it that we built the whole site in 11 pixel size. Not because we want it so small, but that is almost the standard size for majority screen resolution – 800×600.

Data from W3 Schools
But today, we are going forward, no more 800×600 or even 1024×800. Those resolution takes the 11 pixel Verdana nicely, big enough to read.
Today, we are heading to at least 1280×800 screen resolution, or standard desktop monitor will be 1600×900, double the previous resolution. So it is time to adjust the size of your web text. Even WordPress default theme started with 12 pixel Verdana to currently approximately 16 pixel Arial.
11 pixel should be used some other places than the body copy or even, navigation; 11 pixel should be on your footer where it state your copyright; 11 pixel should be in your privacy policy to hide it from people reading too clearly (Evil I know).