Usernames in bold?

[IceShadow1199]

I was checking how many people were online and I saw some people's usernames in bold, what does that mean?

Crash, Magikrazy and YoshiGo999 had their usernames in bold.

 

[Nabber]

Means you put them on your friends list.

 

[IceShadow1199]

Oh, okay thanks.