(written from a Production point of view)
Paramount Home Entertainment (PHE, formerly Paramount Home Media Distribution, and originally Paramount Home Video and Paramount Video) is the home media format distribution arm of Paramount Pictures.
Until 2007, it distributed all home video products stemming from Star Trek films and television shows. It was founded in 1976 as "Paramount Home Video". One of its first presidents had been Mel Harris, who went on to play a major part in the history of the Star Trek franchise.
Star Trek releases
After the late 2005 split of the old Viacom conglomerate, Paramount lost the Star Trek franchise to CBS Corporation, but continued to disseminate Star Trek home media formats for the time being, until CBS had its own, newly restructured distribution arm, "CBS Home Entertainment" in place as of 2007. And while Paramount has retained a license to continue to produce Star Trek films, home media format releases of these fall under the auspices of the distribution arm of CBS, even though Paramount's one is co-entitled.
The UK division of PHE was responsible for Star Trek VHS releases in the UK from 1999 to 2002, and DVD releases from 2002 onward. PHE took over distribution from CIC Video, who were merged into PHE following the end of the joint venture with Universal Pictures.