A faucet is a site that provides drips of satoshis (1 satoshi = 0.00000001 btc) or other cryptocurrencies that are deposited into the wallet of your choosing.
Many of these sites require that you purchase offers or preview websites, etc.
I have limited available monthly data on my current plans, so I will not be going too deep into those.
There are faucets that simply require you to complete a Captcha to collect, and allow you to collect based on a timeframe (i.e. once per 5 minutes, 15 minutes, 1 hour, etc.)
Some faucets require that you register your wallet with a hub site that will handle the transactions to deposit into your account.
There are many faucets out there, and too many that are pop-up magnets. But if you're looking at incrementally building your crypto, and you have the time, they might just prove to be worth it.
Faucets I've used with success are as follows:
As I mentioned earlier, there are other ways to earn coin. This includes viewing web pages or navigating through or directing people through URL shortening ad sites. I don't use the URL shorteners on this site because I find navigating through them to be rather annoying. But, you are free to do so if you please.
Keep in mind that many of these sites require you register with a wallet address that has been confirmed/registered through sites like FaucetHub.io.
CoinAdder is one of these sites that will even give you 500 satoshi (0.00000500 btc) just for signing up!
Again, this can consume bandwidth/data and does require time and dedication. Most sites do use some form of Captcha to reduce automation and keep the playing field level. But, if you're willing, then it can add up nicely.