An esport is any video game — typically multiplayer — played competitively in front of spectators, and usually by professionals. Esports can cover the smallest local and regional contests all the way up to global leagues with prizes in the millions.
There are many genres of esport, including:
First-person shooters such as CS:GO and Valorant
Real-time strategy games like StarCraft 2
Virtual sports games like FIFA and NBA 2K
MOBAs including Dota 2 and League of Legends
Battle royale games such as PUBG and Fortnite