Dealing with web developing projects require those who wish to be referred as web developers to have an advanced knowledge/skills in:
HTML/XHTML, CSS, JavaScript
Server/Client side architecture
Programming/Coding/Scripting in one of the many server-side frameworks (at least one of: Perl, Python, Ruby, PHP, CFML - Coldfusion, Java, ASP, .NET, .NET MVC)
Ability to utilize a database
- Wikipedia