Microtransactions are big business at Activision Blizzard. The company said today in an earnings report that revenue from "in-game net bookings," which include things like DLC sales, loot boxes, and in-app purchases on mobile games, reached $4 billion for 2017. During the fourth quarter alone, Activision Blizzard brought in over $1 billion for in-game net bookings. These figures represent quarterly and annual records for Activision Blizzard.

Importantly, as analyst Daniel Ahmad explained on Twitter, around $2 billion of Activision Blizzard's annual revenue from in-game net bookings came from the company's mobile subsidiary, King, which operates Candy Crush. The other $2 billion came from Activision Blizzard's console and PC efforts, along with Activision Blizzard's efforts on mobile such as Hearthstone.

It's worth noting that around $2 billion of that is indeed from King's mobile games such as Candy Crush.

But that still leaves another $2 billion from console and PC games add on content. — Daniel Ahmad (@ZhugeEX) February 8, 2018

Call of Duty: WWII offers microtransactions in the form of Call of Duty Points, which can be spent to unlock loot boxes that contain cosmetic items. Additionally, Activision recently launched the game's first paid map pack, Resistance. In Overwatch, players can spend money on loot boxes that contain things like skins and sprays. World of Warcraft has a significant in-game economy as well, as players can purchase things like mounts and pets for real money, among many other things.

Activision Blizzard is not the only publisher that makes a lot of money from microtransactions. Electronic Arts, which found itself in hot water regarding Star Wars: Battlefront II's use of microtransactions, reported $787 million in what it calls "live services" for the latest quarter.

Additionally, Grand Theft Auto and Red Dead parent publisher Take-Two Interactive said this week that GTA Online and NBA 2K18 recently set records for what the company calls "recurrent consumer spending." Take-Two CEO Strauss Zelnick at one time referred to GTA Online as "the gift that keeps on giving" as it relates to the money it makes from the game's microtransactions.

For Activision Blizzard, EA, and Take-Two, each company reported year-over-year gains for microtransaction revenue. While such systems can be highly controversial, it is clear that they are popular and people are willing and eager to spend.

For more on Activision Blizzard's earnings report today, check out the stories linked below.