A beta is any software still under development that is made available to a select few to test, examine, and report problems they face. Beta testing allows developers to find problems they may have missed and fix them before the program is released.
Closed beta vs. open beta
Often there are two beta testing phases, open beta and closed beta. An open beta also known as a public beta is beta testing open to any user, who is known as a beta tester. Closed beta is beta testing only available to a select few individuals or only company employees.
How to be a beta tester
Many games (especially online games) in the final stages development have an open beta for several months that allows anyone interested in the game to play and report problems. To become a beta tester for any program or game requires either a registration or sometimes only a download of the program from the companies website.
Tip: Participating in a beta is always free and should never be purchased. Many scam artists will sell a copy of a beta program or the code to get into a beta to unsuspecting people wanting to play a game before any of their friends. Many times these codes are fake or disabled codes to play the game.