Bitcoin is a type of crypto currency, one that has gained much ground over the years. What makes it a good investment, is its growth pattern over the past years since its creation in 2009. In it's early stages, investors who took the opportunity stood to gain much. Bitcoin investment works this way, you purchase bitcoins from any market that sells them (you should be careful on that though, because the trade has been a little tricky), however after trading you hold onto the coins for a while, until they raise in value then you sell them for a higher price. It does involve some speculation, but if you follow study the patterns, you will stand to gain much.