LOS ANGELES - Ticketmaster, often the target of fan anger when tickets to popular concerts get sold out in seconds, is removing an annoyance that can slow down the buying process: the jumble of letters that people need to decipher known as Captcha.

The puzzles provided by Google Inc. are meant to deter automated systems known as "bots" from purchasing large numbers of tickets the instant they go on sale. Scalpers have been known to employ bots to acquire tickets, which they resell for a profit.

Captcha is an acronym that stands for "Completely Automated Public Turing test to tell Computers and Humans Apart." Since only humans, not computers, can decipher Captcha codes, websites install the systems to keep tickets out of the hands of large-scale scalpers. In the fight against more sophisticated bot operators, Captcha codes have become more difficult - so difficult that the puzzles started slowing down flesh-and-blood fans.

Take a recent Captcha puzzle, which looks like a bunch of distorted letters that is meant for a buyer to interpret and type: "dsrific LCDAppr." Because of the way the letters are bent out of shape on screen, it's tough even for humans to tell if the two instances of "p" are capitalized or not.

In the next several weeks, Ticketmaster will replace all its online puzzles with easier ones provided by a startup called Solve Media. On mobile devices, Ticketmaster is eliminating the need for puzzles entirely, by verifying the user through a "push" notification.

Fans using the website will now see common phrases or multiple choice questions, and a drop-down menu of answers. Solve Media looks for digital clues - which it won't divulge - to determine if the ticket-buyer is a person or a bot.