to tell Computers and Humans Apart, is a type of challenge-response test used in computing to determine whether or not the user is human. This test is comprised of a series of symbols, (letters, numbers, or punctuation marks) that certain websites require in order for a person to post or view information on the internet. When a CAPTCHA appears on the computer screen during Internet usage, the user must type in the symbols that appear; Doing so ensures that the command is being performed by a person, not a software program running automated tasks online. In Internet vernacular, these types of programs are referred to as bots. CAPTCHA usage significantly reduces the volume of spam a bot might produce. Often utilized in online message boards and blog comments to prevent bots from posting links as a comment or message, CAPTCHAs have also been used to prevent people from using downloading large quantities of data from multimedia sites. When encountering a CAPTCHA online, users are instructed to enter the characters exactly as they are displayed on the screen.