The National Trust for Scotland (NTS) own all the islands that make up St Kilda. They were given to the NTS in 1957 by the owner who wanted the islands to be kept as a bird reserve and special wild place. In the summer there are NTS staff living on the island:

NTS Ranger
The NTS ranger looks after the wildlife on the islands, welcomes visitors & helps look after work parties

NTS archaeologist
The NTS archaeologist looks after all the old houses, cleits and other archaeological remains, welcomes visitors and helps look after work parties.

Seabird and Marine Ranger
The NTS Seabird and Marine Ranger counts the numbers of seabirds on the islands, watches for sea life, welcomes visitors and helps look after work parties.
Work Parties are groups of people, organised by the NTS, who volunteer to go to St Kilda for two weeks every year and help to look after and repair the buildings. They also just enjoy living on these islands for a while.