Different Types of Comments

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/different_types_of_comments.htm]

Programming enterprise apps and their supporting processes, I've used at several languages. Most of them have different ways to make comments.

Characters	Languages	Multi-line vs. Single-line	Characters
//	C#, JavaScript	Single	2
/*  */	C#, SQL, CSS	Multi	2,2
'	VB	Single	1
REM	DOS	Single	3
	XML, HTML	Multi	4, 3
<%-- --%>	ASP.Net	Multi	4, 4
--	SQL (single line)	Single	2

I didn't have any big dialogue on this, I just found it interesting - 7 different ways to comment code for a set of languages that are often used together for a common goal. I'm sure that someone with a strong Compiler background could explain the significance of multi-line comments vs. single-line comments, and number of characters involved to create the comment identifier.