Civilian community support officers (CSOs) focus on low level crime, disorder and anti-social behaviour.
CSOs can detain but not arrest suspects
They are supposed to allow detectives to concentrate on more serious crimes.
Unlike police officers, CSOs are not called away for tasks such as court appearances, public order policing or case management.
As a result they tend to have a consistent presence in the community.
CSOs can detain a suspect for 30 minutes but not arrest them.
They can also complement the work of officers by releasing them from tasks that do not require the full range of policing skills.
These include guarding the scenes of serious crimes, safely escorting abnormal loads and stopping vehicles for safety inspections.
Despite their differences CSOs are held accountable in the same way as police officers, and they are subject to the Independent Police Complaints Commission.
About 3,500 currently operate in England and Wales.