Initially faucets were created in order to spread the adoption of Bitcoin around the Internet. The original Bitcoin faucet was made by then Bitcoin Core developer Gavin Andresen and, believe it or not, it used to dispense 5 whole Bitcoins to each user.
Since then faucets have become more business oriented. Today, faucets are sites that dispense a small amount of Bitcoin to users every few minutes while making money from displaying ads to these users. As long as the site owner is making more money from ads than what he’s giving out to his users, he remains profitable. Most faucets either pay out directly to your Bitcoin wallet or use a 3rd party micropayment wallet like CoinPot or FaucetHub.
While this might seem to be a hassle at first, it’s actually a great convenience since you have all of your claims concentrated in one or two sites. This makes it much easier to withdraw and track your money. Also, since the faucet industry is known to be a bit shady, things can change relatively quick. So, make sure to check out the terms of each faucet you use.
Here are the main things to look out for:
Claim amount – How many Satoshis do you get per claim?
Timer – How long do you need to wait between claims?
Minimum withdraw – What is the minimum amount from which you can withdraw your balance?
Withdrawal method – Are payments done directly, or through a micropayment wallet?
Referral fee – What’s the fee you get for referring new users to the faucet?
Source : https://99bitcoins.com