sRGB
From Just Solve the File Format Problem
sRGB is a standard color space (a way to encode colors as numbers) developed by Microsoft and Hewlett-Packard.
It is widely used on the web, and by computer monitors. Many standards such as HTML and CSS define their colors in terms of sRGB.
Many image creation workflows do not do sophisticated color management, so image files often use sRGB in practice, whether or not their specification says they should.
The biggest drawback to sRGB is probably its relatively small color gamut.
