The Head is an essential part of many starships. It allows cremembers to relieve themselves while on duty quickly and efficiently, without necessarily having to go through rooms or other compartments. There are several types of heads, from the simple toilet, to the full on restroom and even the bathroom.
The Toilet type head is the simplest, being a small room which contains a toilet. Compact in nature, they can be placed in just about any extra space, and come in many shapes and sizes.
The Restroom style head is a larger version of the toilet, which contains two or more stalls, as well as sinks. These take up much more space and must be a dedicated compartment designed into a ship from the start.
Bathroom style heads are multi-purpose compartments, which contain both toilet stalls and showers, along with sinks and lockers for bathers to store gear in. These rooms are rather large and must be specifically planned into a ship's design.
Bathhouse heads barely fit into the category, not actually containing toilets of any kind. These are more of a luxury item, and cannot fit on many types of ships due to the size needed to be dedicated to them. They contain Bathtub stalls, shower stalls, and even Yamataian-style communal baths. A Bathhouse has a small compartment with lockers for gear such as towels and changes of clothes to be stowed.