Techstep is a sub-genre name from the late 1990s. You will hear modern producers and DJs use the term but it specifically refers to a historical sound.

The era

1997-2002. Ed Rush, Optical, Trace, Konflict, Dom & Roland. The Virus Recordings catalogue is the canonical reference. Dark, mechanical, sub-heavy DnB built around the Reece bass.

The modern usage

When someone calls a current track "techstep", they usually mean it sounds like it could have been released on Virus in 1999. The aesthetic is recognisable; the term has become more about lineage than about literal genre membership.