Every year of high school, there is a dance and an American football game referred to as homecoming. It is similar to prom. Students vote on homecoming king and queen. It is a popularity contest jaja

Some of the specifics might depend on where you live (country and area). I believe this is a tradition in Canada too, so it might be recognized elsewhere.
I know it as a tradition in the US. Here, things can vary depending on the region, state, the school district, the school/town/university and such. 
In my area, there is an annual event- usually an American football game, other sporting event or banquet- where graduates and current students celebrate their school/town (or university).  People come home for this occasion so it is called Homecoming.  Usually, there is a parade or performance by the school’s marching band and a Queen and often a King and a court (other deserving students) are crowned.  While popularity is certainly helpful, most schools have requirements that all candidates must meet before they can be considered.  There is often a Homecoming Dance too. 
Before high school graduation, there is a special dance for those who will graduate.  Students in 12th grade (the last year of high school) are called seniors.  The dance is called the senior prom. 
Most high schools in my area, also have a dance for juniors (students in 11th grade).  This is the junior prom; it is usually less formal. 
The word “prom” is usually used for the upper grade dances. 
Freshmen (9th graders) and sophomores (10th graders) might also have dances.  Proms tend to be more formal (and more expensive).