Which one should we use to respond to someone's "thank you" ?

 

"You're welcome!"

 

Definately you are welcome OR you're welcome.

 

It's spelled difinintely. There is NO A in that word.

 

No, it isn't. It is spelled "definitely".

You might also want to note that this thread had been dormant for nearly five years.

 

Definitely.

Welcome to the forums!

 

Actually, I'm fairly sure it's spelled "definitely." There are two i's in it, not three.

(But welcome to the forum anyhow. We all have a finger slip from time to time!)

As to the topic of this thread: I once had a colleague who always wrote "your welcome." It made me cringe.