Mingtongzhi has made a great series of videos giving players an idea of what zoning is in Street Fighter 4. The video below covers what start up, active and recovery frames are and it makes great use of slow motion to display the assumed hit boxes for moves so you can see what exactly is going on.
While this isn't hardcore advanced stuff, if you're not familiar with these concepts, this is a very helpful guide, although there's a few things that are not exactly accurate.
