I am sure you have been confronted by visuals such as this one, blocking your passage on some secure internet web site. That is, until you type in the coded message you see.
This image is called a "captcha," an acronym for Completely Automated Public Turing Test to Tell Computers and Humans Apart. Its goal is to prevent an automated script of "spam bot" from intruding illegally on a secure page.
Many people and companies are attempting to both improve and defeat the growing use of visual captchas. At times, the best captchas become too difficult for even humans to read.
However, they should call on mathematics teachers, as we learn to become quite adept at deciphering student homework papers, which often look like captchas.