So, I am getting into web design, I am learning HTML, and CSS...is it practical to learn javascript, php, ajax, mysql, etc. as well? or is it more practical to choose one and stick with it? and if so, which one would be best? and what are the main differences between them?...and please dont say "you should learn as many programming languages as you can" sure. but I am trying to be practical...I want to know about the languages as well and which one is most practical or most useful or whatever...I know very little about them...