ROM, or range of motion, is a commonly used term referring to how far a specific part of the body (e.g. joint or muscle) can be stretched or moved. Achieving a generally high range of motion can prove greatly beneficial for any sport, discipline, or exercise routine, and is even proven to come in useful for general household tasks.
Gymnastics is a particularly beneficial class or training style for those looking to improve their range of motion, or extended range of motion, without the burden of an external load. CrossFit style gymnastics in particular is accessible to all ability levels, teaching, exercising, and improving upon appropriate variations of bodyweight movements such as kips and muscle-ups.