Having just about got to grips with HTML, I am now looking to broaden my horizons with some web programming.

Can someone please tell me what are the relative merits of JavaScript, VBScript, CGI, ASP, PHP3, etc?

Under what circumstances should you use one of these particular facilities?

What is the decision-making process when deciding which to use?

I realise that my question is broad enough to write a thesis on, so any web site references would be welcome.

Thanks in advance.