What is hm?

It seems like your request is a bit vague. "HM" could refer to a variety of things depending on the context. Here are a few possibilities:

1. H&M: Hennes & Mauritz AB, commonly known as H&M, is a global fashion retail company known for its affordable and trendy clothing. It is one of the largest fashion retailers in the world, offering a range of apparel and accessories for men, women, teenagers, and children.

2. His/Her Majesty (HM): In the context of royalty, HM is an abbreviation for His Majesty or Her Majesty. This is used to refer to kings or queens in monarchies.

3. HM (in Pokémon): HM stands for Hidden Machine in the Pokémon video games. These are special items that teach Pokémon new moves, which often allow the player to overcome obstacles and explore new areas.

4. HM (Heavy Metal): In music, HM might refer to heavy metal, a genre of rock music that developed in the late 1960s and early 1970s, known for its loud, aggressive sound.

5. HM (Harmonic Mean): In mathematics, HM stands for the harmonic mean, a type of average calculated by dividing the number of values by the reciprocal of each number in the series.

If you could provide more context, I would be happy to give you more specific information!