What does Poke mean in Facebook ?

Poke on Facebook is saying Hi or Wassap !! to your friends and relatives but some people take Poke as a sign of annoyance or disturbance but the real meaning and purpose of Poke is 

1. A “Poke” is basically someone trying to get your attention
2. It’s one of the meaningless features that are used just to annoy someone
3. If you Poke someone not in your network and they poke back. You can view their profile even if your not their friend!
4. A Poke is when you allow someone to see your facebook page for 3 days, so they can know who you are and hopefully add you as a friend