Single Room Occupancy or SRO is the renting of a house room by room. This is similar to a boarding house where there are very few communal common areas. Typically a fixed price for one person per room, and a slightly higher rate for two people in one room.
Single Room Occupancy can be a great rental property investment strategy given the ability to maximize a dwelling's rent revenue. For example, a 2,500 SF 4 BR single family residence that rents for $2,000/month can be converted into an 8 BR SRO that generates $500 per BR or $4,000 per month in rental income.