Feta is a Greek fresh cheese which is brined and made from usually either sheep's or a mixture of sheep's and goat's milk. The name feta is usually associated with Greet feta, but the style of cheese is actually pretty common in the along the Mediterranean, Balkans, and pretty much everywhere there are sheep and salt.

That being said, feta has been granted a protected designation of origin (PDO) by the European Union. This process is basically a trademark for protecting the "feta" brand from individuals that might produce feta-style cheese outside of the areas of Greece specified by the PDO certification. It's the same deal as how champagne can only be called champagne if it's produced in a certain area of France--everywhere else it is produced it is called something else, typically "sparkling wine." Feta when produced in other areas is called many things, but more often than not, simply "white cheese" or "sheep cheese."

Greeks probably earned the PDO status because they eat feta with most of their meals. There were viral facts about how much cheese Greek people eat, cited as around 24 kg (52 pounds) per person per year, which is one third the average body weight in Europe. It's not a small amount.

Does feta melt?

Not really. White cheeses (e.g. feta, halloumi, paneer, etc.) are too moist and acidic to melt. So, feta is not a fondue cheese, but baking or pan-searing feta does give it a great flavor. Saganaki is a really popular snack that can be made of sheep's milk feta or other Greek cheeses (halloumi, kefalotyri, kasseri, etc.) which is pan-seared and usually served with lemon juice and pepper.