telefax

Telefax, often shortened to fax, is a telecommunications technology for transmitting scanned printed material, usually existing documents, on which paper is scanned, transmitted as a signal by telephone or other telecommunication line, and printed at the receiving end. The technology was first developed in the mid-19th century, with early devices using mechanical systems to scan and reproduce images. The term "fax" is derived from facsimile, meaning "faithful copy."

The modern fax machine gained popularity in the latter half of the 20th century, becoming a ubiquitous tool in businesses and homes. A fax transmission involves a sending machine scanning a document and converting it into an electrical signal. This signal is then sent over standard telephone lines to a receiving machine, which decodes the signal and prints a copy of the original document. Fax machines typically use thermal paper or plain paper for printing.

While the advent of email and digital document sharing has reduced the reliance on fax technology, it remains in use in certain sectors, such as healthcare and legal fields, where the transmission of official documents with a verifiable record is often required. The security and immediate nature of fax transmissions are still valued in these contexts. The underlying technology of converting visual information into transmittable signals has also influenced later digital imaging and communication systems.