The rise of mobile payments technology truly began in 2014 when Apple Pay hit the market. At the time, it was the only major mobile wallet out there.

But in the last two years, mobile wallets have flooded the market with offerings such as Samsung Pay, Chase Pay, Android Pay, Microsoft Wallet, Walmart Pay, and Kohl’s Pay. Each of these offers unique benefits to the user and encourages customers to form shopping habits around them.

And so far, they seem to be succeeding.

BI Intelligence, Business Insider’s premium research service, finds that mobile payment volume will reach $75 billion this year. That figure should swell to $503 billion by 2020 thanks to advancements in mobile payments technology.

Below, we’ve outlined how mobile and contactless payments work and explained the different types of payments technology that are shaping the present and future.