NEED FOR CAPTCHA

When you creating an account in any website you are prompted to enter the words given in the picture in the box as it is.This is called captcha.It is necessary because some software will create numerous number of account which the account providers doesnt like therefore they provide captcha which will not be identified by the software.In gmail when you enter the wrong password for five times it will request to fill the captcha this is because there are softwares that will try all the combination of words and numbers to hack the account.