An eBook, or "electronic book", is a publishing format by which a book is created, distributed and read as a computerized file, as opposed to being printed on paper and bound.
Most recent Star Trek books are released simultaneously as eBooks and in traditional print formats. An increasing number of older Trek titles by Pocket Books that are no longer in print as physical books are also available as eBooks. However, titles identified as eBooks in this wiki are primarily works that are released exclusively in electronic format, such as the Star Trek: Starfleet Corps of Engineers series. These works are reprinted in physical omnibus books at a later date.
Until 2006, the only literature released exclusively in eBook format was the SCE series. With the relaunching of the series to Star Trek: Corps of Engineers, a reduction was made to the number of stories in the series, to make room for other eBook projects. The first such events were two miniseries each celebrating the anniversaries of TOS and TNG: Mere Anarchy and Slings and Arrows.
At the conclusion of the Slings and Arrows miniseries in early 2008, Pocket Books put the line of original eBooks on hiatus. 
Pocket revived the original eBook in 2011, with the release of The Struggle Within. Lust's Latinum Lost (and Found), the first original Star Trek: Deep Space Nine eBook, was released in 2014, with a second, Rules of Accusation, released in 2016.