Eliza was first developed from 1964 to 1967 at MIT by Joseph Weizenbaum. Named after Eliza Dolittle, from George Bernard Shaw's Pygmalion, or My Fair Lady.
It was created to explore communication between humans and machine. Apps like this are usually referred to as chatbots
I developed Eliza using php and mysql in the 90's to use as a parlor trick. It was mostly admired by young children and some people familiar with computing were curious about it.
Most realized, after a short time, that she really wasn't really a psychotherapist, or even useful at all, due to it's limited data tokens(keyword and response phrases), random response string repeats, and the lack of focus to a subject
ELIZA starts its process of responding to an input, by first examining the text input for a keyword(s). The input sentence is then manipulated and transformed, sometimes picking part of the string as a relative subject, then the resulting string is combining with randomly selected response strings that have been associated with the keyword(s). If there are no keywords found, a generic reply is given.