A computer is distinguished from a calculating machine, such as an electronic calculator, by being able to store a computer program (so that it can repeat its operations and make logical decisions), by the number and complexity of the operations it can perform, and by its ability to process, store, and retrieve data without human intervention.

Data entry is entering data into the computer, which includes keyboard entry, scanning and voice recognition. When transactions are entered after the fact (batch data entry), they are just stacks of source documents to the keyboard operator. Deciphering poor handwriting from a source document is a judgment call that is often error prone. In online data entry operations, in which the operator takes information in person or by phone, there is interaction and involvement with the transaction and less chance for error. A person who enters data into the computer via keyboard or other reading or scanning device is known as a computer operator.

Data entry is required for data processing or information processing, operations (e.g., handling, merging, sorting, and computing) performed upon data in accordance with strictly defined procedures, such as recording and summarizing the financial transactions of a business. In automatic or electronic data processing the operations are performed by a computer device, capable of performing a series of arithmetic or logical operations. In distributed data processing some or all of the operations are performed in different locations at computer facilities connected by telecommunications links.

In some companies the need for data entry is constant while for others there may be just a temporary requirement. Whatever the need may be, accurate and easily accessible data is a necessity. In addition, whether it is a small business or a sprawling global empire, clients are lawyers, hospitals, state courts houses, oil companies, transportation companies, Ivy League colleges, pharmaceutical companies, universities, and publishing companies among others.