Awhile back I didn't know what it was either, so don't feel ashamed about it. What masturbation basically is, is when you are fingering or rubbing yourself "down there".
Since I do not know your gender I'll explain it from both genders. When a male wants to masturbate, he basically rubs his penis up and down, making himself ejaculate. For a girl, she fingers her vagina, like rubbing it up or down, or side-to-side -- whichever makes her feel more sexually stimulated.
The main purpose of masturbation is for the sex drive. People masturbate for all kinds of reasons. He/she may want to do it as an escape, because masturbating is known to relieve anxiety or stress. Some just do it to for the lust of sexual stimulation.
Attention: NOTHING on this site may be reproduced in any fashion whatsoever without explicit consent (in writing) of the owner of said material, unless otherwise stated on the page where the content originated. Search engines are free to index and cache our content. Users who post their account names or personal information in their questions have no expectation of privacy beyond that point for anything they disclose. Questions are otherwise considered anonymous to the general public.