It is difficult to identify any peculiar device as the earliest computer, partly because the word "computer" has-been been subject to varying interpretations over time. Originally, the term "computer" referred to a being who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device.
The defining feature of latest computers which distinguishes them from all other machines is that Computer Consultants they can be programmed. That is to say that a checklist of instructions (the program) can be given to the computer and it will store them and carry them out at some day in the future.