This visa form falls under the UK settlement route
This visa type allows these types of settlement applications:
Spouse or civil partner of a person present and settled in the UK
Unmarried or samesex partner of a person present and settled in the UK
Parent of a child present and settled in the UK
YOU NEED TO BE APPLYING UNDER ONE OF THESE CATEGORIES:
Family life as a partner (2 year route - you were last granted limited leave of 27 or 24 months under Part 8 of the Immigration Rules and have completed at least 24 months with such leave)
Family life as a partner (5 year route - you were last granted 30 months limited leave as a partner under Appendix FM and have completed at least 60 months with such leave)
Family life as a parent (5 year route - you were last granted 30 months limited leave as a parent under Appendix FM and have completed at least 60 months with such leave)
Depending which visa you currently hold, will determine what evidence you need to submit to UKVI