Do high schools have military companies?

I read somewhere about military companies in high schools. Is this a thing? How do these work, and are there any existing in modern schools?

When people refer to "military companies" in high schools, they're likely referring to Junior Reserve Officer Training Corps (JROTC) programs. The JROTC is a program sponsored by the United States Armed Forces in high schools across the country, and even at some private and public middle schools.

The JROTC curriculum includes education in citizenship, leadership, social and communication skills, physical fitness, and wellness. In addition, while there is an element of military culture – such as maintaining discipline and wearing a uniform – it doesn’t necessarily serve as a direct pathway into military service. Although some students might indeed go on to serve, participation in JROTC doesn’t entail a future commitment to the military.

These programs can provide students with valuable skillsets and life experiences. Indeed, they can instill a sense of discipline, responsibility, and citizenship, which can benefit students in many walks of life beyond the military.