Gambling with bonus is a great way to try out a new gambling platform, most of the sites where I have signed up, did have some kind of free bonus to kickstart my gambling.
Faucet, i think is a strategy by online casinos to let their customers feel/try their games for free thus enticing them to bet with bettor's own money if they are already comfortable with the site.
@XinXan
My question is, sites offering free bitcoins, are they legit?
They are legit, of course, the ones I have listed on the OP are totally legit, Freebitco.in being the best one when it comes to free Bitcoin since you actually get the full amount with no requirements whatsoever, you can withdraw your free bitcoin at any time but there is a min withdrawal amount. You can also gamble with them at any time and withdraw winnings at any time, no roll-over or other requirements aside from the min. withdrawal.