sheet music?

Do i need to know how to read sheet music to play the guitar?

In a strict sense, no, but it depends on what you mean by playing guitar.

If you just want to play popular music (i.e. rock, blues, pop, and other non-technique stuff) then reading music is not a necessity. If, however, you want to get into more complex musical forms, such as jazz and classical, then reading music is a must.