There are many different types of Betta but the splendens type is the most popular. Its popularity came from its ease of breeding new colors and its aggressiveness. It is referred to as the siamese fighting fish because they were bred for their fighting ability. 
The ancestor of the modern betta can be found in the wide shallow expanses of rice paddies, and swamps. They come from southeast asia. Some countries include Thailand, Cambodia, and Vietnam. 

Bettas are relatively easy to care for and with the proper start can live up to 5 years.

Bettas should be kept in a tank that is at least 5 gallons. The tank should be equipped with a filter, heater, and thermometer. Maintaining a stable water temperature and quality is important for a long happy life.. Avoid placing bettas in bowls or small containers. These do not provide enough space or proper heating for the fish.
Bettas are sensitive to poor water quality, so it is important to perform regular water changes. 20-25% of water changed weekly should be fine. You may also want to monitor the water parameters with a test kit. Bettas prefer warm water, with a temperature range of 75-80°F being ideal. I keep mine at 78°F.

Bettas are carnivorous and require a diet that is high in protein. Commercial betta pellets or frozen or live foods such as brine shrimp, bloodworms, or daphnia are suitable options.
Be careful to not overfeed your Betta. They have small stomachs and should be fed small meals 1-2 times per day. Overfeeding can lead to health problems and poor water quality.

Bettas enjoy having hiding spots in their aquarium. Adding live plants, artificial silk plants, caves, or decorations can  help to reduce stress, and improve the overall health of the fish.
Keep away from the plastic plants. Betta fins are very fragile and may get ripped on sharp edges.

Bettas are usually best if kept by themselves however there are some that do well in a community setting. It will all depend on the individual Betta and the other fish you add with him.
Two male Bettas should never be housed with one another; They will attack each other.
Female Bettas may be housed together in sororities. You will need a larger tank, preferably no less than a 15 gallon, and no less than 5 females. Females must be kept in odd numbers.