What is an Turing Machines?

A Turing Machine is theoretical device of significance in computer science. It has a tape which extends infinitely in both directions and a recording head which can read and write one symbol at a time on the tape. The number of symbols it can read and write is finite. The head can also move in either direction on the tape one step at a time. The machine also a finite set of rules and a memory. Each rule takes the current symbol on the tape in combination with what is in the memory and from that says what symbol should be written, what the new content of the memory should be, and which direction the head should move. The device is significant because it is believed that any problem which can be solved by any computer can also be solved by a Turing Machine. Thus, a Turing Machine is considered a sort of minimalist computer. Also, devices or computational systems which are believed to be capable of solving these generalized problems are said to be "Turing Complete".