Notice: For the purposes of this article, the term "tech map" will be treated as an umbrella term that includes all of these definitions.
Technical maps (often shortened to "tech map") is a term that does not have a clear, agreed-upon definition amongst the osu! community. Depending on the user, "tech map" can be as broad as a beatmap that simply contains non-generic beatmap patterns, or as specific as a beatmap that is dense in object count and contains many irregular slider shapes that quickly and drastically change speeds (often at high intensity).
Tech maps are most often associated with song genres that offer complex and fast-paced sounds (e.g., drum-and-bass, dubstep, and drumstep) as they often allow for the mapper to explore each and every individual sound in-detail to the beatmap's advantage. Although music of this type is not explicitly required.
Regardless of definition, many players claim that tech maps are unfair (in terms of skill) due to the main increase in difficulty deriving mostly or solely from the confusing patterns or irregular sliders. Likewise, this means that they are not very popular for gaining large amounts of pp at once due to the way the current system works and how it undervalues beatmaps of this nature.
Due to the broad nature of the term "tech map," there are many different aspects that could describe the term. The lists below describe different definitions from popular "types" of players.
Notice: The "broadest" definition only requires one or two of the aspects listed to be present in order to define a beatmap as tech.
Non-generic beatmap pattern
Beatmap pattern with a hard flow
Good examples of tech maps that fit this definition are Silentroom - Nhelv (Nyxa) [iniquitatem] and RUMI - Densetsu no Matsuri (Net0) [Oni].
Notice: The "most restrictive/specific" definition requires all of the aspects listed to be present in order to define a beatmap as tech.
Difficult-to-read pattern
Irregular slider shape (SV slider)
Good examples of tech maps that fit this definition are Camelia - Exit This Earth's Atomosphere (Camellia's "PLANETARY//200STEP" Remix) (ProfessionalBox) [Primordial Nucleosynthesis] and LeaF - MARENOL (Yugu) [Extra].