Intro to Semi Hydro?

[swords]

I'm new to the term/idea of Semi-Hydroponics. As I page through the posts here it looks like most of you are growing in undrained clear containers of Leca or Hydroton. Do you ever eventually drain these pots or just let them go until dry? Do you use hoses and pumps or just fill with water/fert solution? Do the plants grow faster this way to blooming than potted or mounted or pretty much about the same?

Is there a good introductory starter page or post here that explains what you guys are doing and why?