Is it inappropriate to say "you know" during a conversation

I wanted to know if is it inappropriate to say "you know" during one's conversation, because I got this mania from Tv series and movies. I don't use it that much, but always when I want to gain some time to think in the words that I'll use next I say "you know", it's like I time spender to me.

I hope I have made myself clear. Thanks in advance.

I'll be very grateful if you correct my wrongs.