HUD is an acronym for Heads-Up Display, an online poker tool used to collect and display statistics of other players at your table.
There are many different types of poker HUDs out there, but most of them provide you with similar stats, giving you a quick insight into the opponents’ tendencies. Some of the most popular stats you’ll find in a HUD are VPIP (how often a player gets involved with a hand), PFR (how often they raise), 3-bet (what’s their 3-bet frequency), etc.
A poker HUD displays all this and other similar information in an easy-to-read way, helping you to make your decisions and adjust your strategy based on the player’s tendencies. You can also move things around and personalize your HUD to make it even more useful.
It’s important to note that in this day and age, not all online poker sites allow HUDs, and some of them only allow you to use an integrated HUD that comes as a part of the poker software.