Bitcoin faucets (they can be for any cryptocurrency) are a reward system, in the form of a website or app, that dispenses rewards in the form of a Satoshi (1 Satoshi = 0.00000001 BTC) for visitors to claim. These rewards are dispensed at various predetermined intervals of time. And can be claimed by either completing a captcha or task as described by the website. There are real faucets giving away hundreds of dollars! Just find your way and try the proven ones :)
Rewards are in place to attract visitors to the faucet’s webpage. These faucet sites usually contain advertisements. Advertisers pay the faucet owner to display these ads on his site. Advertising costs are calculated on Cost per Thousand impression (CPM) basis.