A forex mini account is a forex account that trades on less than the standard $100,000 lots. In the past forex trading was something that only large corporations, banks, and wealthy individuals were able to participate in.
When retail forex trading came into existence brokers realized that not everyone was going to want to leverage $100k a trade when trying to learn or trying to make a little side money. Thus, the invention of the forex mini account was almost mandatory.
Forex mini accounts trade in lots of $10,000. The pip value varies, but they are usually worth around $1 for every pip. This is a far cry from the average $10 per pip value of a standard lot trade. Even if you had big plans of trading the big dollars some day, a mini account will allow you to learn about what you're doing before you run off and try your hand on the big market.
Forex mini accounts work on the same market that everyone else trades, they are just easier numbers to deal with for new traders.
One typical thing to watch out for when considering opening a forex mini account is to not open with the minimum required balance by the broker. Many brokers will open a mini account for you with only $300 of capital. That may seem like a lot of money, but a few mistakes, even in a mini account, and your balance is cut in half and you don't even know how it happened.
If you want to trade on a mini account, start with no less than $1000. If you don't have $1000 to start trading, you could try a variable trade sized broker like Oanda or stick to demo trading until you have more money saved up. It's difficult to resist that urge to jump in, but being under-capitalized is a common mistake made by new forex traders.
Keep it simple, use low leverage, and go slow. Forex mini accounts are common these days among brokers, so shop around, find a broker you like and open a forex trading account if you have the capital. Forex trading is not easy so don't be discouraged If you find it overly complicated at first, everyone does. It's also difficult to make money in the beginning. The best thing you can do is try to avoid common forex mistakes and take it slow.