I got it now why you didn't know. Welcome to DeviantArt, I hope you will learn how to credit artists properly on here. ^^
Everyone has to write "@ + username (or : iconTac0sgirl : without space)" like Tac0sgirl
. if someone wants to use your art unless you wrote TOS about you don't need to be credited.
It's known a basic common sense on here, otherwise, it will be considered art theft.
Writing proper credit shows their respect for the artist and artist's hard work.