Digital 100s are a type of financial derivative, also referred to as binary options.
Essentially, digital 100s are a simplified form of option that offer a yes/no outcome. If the trader makes the correct choice, they will make a defined profit. If they make the wrong choice, they will make no return at all and lose the amount paid to open the trade.
Because they only require a yes/no proposition and a time period, digital 100 options can be traded on a huge variety of markets. That includes not only currencies, commodities, indices and stocks, but also special markets like political elections or economic announcements (such as non-farm payrolls). The length of a digital 100 can also vary hugely, from short-term trades to events weeks into the future.