Underscore in Domain Name

[sanderson]

Does anybody heard about underscore’s role in domain name? I mean does it considered as a space or not.

Are there any issues with it? Because many times site owner don’t get any other option than using underscore.

I know you should avoid using it but most of the email addresses does have one!

What’s the issue – technical, spam etc.? Have any idea? Curious to know.

[Peter]

Are you talking about using an underscore in a domain name? Well, as far as I know, the underscore and the space are not acceptable characters in a domain name. The only characters allowed in a domain name are the 26 letters of the standard alphabet, the numbers 0-9, and hyphens.

[sanderson]

Yes Peter, that's true! But do you know the issue behind underscore, any technical reason?

[Rodney]

Here's the technical reason.
Google sees hyphens as dividers in URLs and ignores underscores.
When underscore is used Google combines the two words on either side of the underscore and makes it one word.
This has been proved by several tests and confirmed by GoogleGuys.