Typically that means that an author or editor uses a computer, usually a word processor, to create or revise or annotate some document. Since publishing is usually a purposeful act of communication, and since the use of electronic technology affects the form and spread of that communication, it is clear that there are social changes that have resulted from the widespread adoption of electronic publishing as one of the key uses of computers. I remember working with punch cards, paper tapes, and magnetic tape word processors in 1967. I proposed automation of stock broker activities and of newspapers. There has long been a battle over how much authors must do vs. what others in the publishing world undertake.
Simple tools are handy for short documents, but long or complex documents require extra work.
While SGML was appealing to publishers, few others found it usable, and the publishing world is still working to add tools and practices so as to reap promised savings when markup is present. In the late 1980s, following the emergence of CD-ROM and further spread of the Internet, multimedia authoring became possible, and even popular due to Apple's free distribution of HyperCard in 1987. Reading from paper is superior to reading from displays, which are too grainy. At the same time, displays will grow in number and size, with several on each desktop, and wall displays becoming more affordable. There will be a wide spread in sizes, requiring more scalable display methods, which are targetted by systems that use markup along with style sheets.