What was the first word processing program used in 1979?

The first word processing program used in 1979 was WordStar. The software was published by MicroPro International and became the most successful word processor throughout the 1980s.

WordStar was not the first word processor ever used, but the first one to become suitable for commercial use. In 1979, Apple released Apple Writer 1.0, a word processor that only displayed text in uppercase. In 1982, WordStar was released for DOS and became the standard word processor for companies. A WordStar version for Windows 3.0 was developed in 1991, but by then Microsoft Word was already established as the new corporate standard.