Prisons in England and Wales are divided into several categories relating to the age, gender and security classification of the prisoners it holds.
Male adult prisoners (those aged 18 or over) are given a security categorisation soon after they enter prison. These categories are based on a combination of the type of crime committed, the length of sentence, the likelihood of escape, and the danger to the public if they were to escape. The four categories are:
A) Those whose escape would be highly dangerous to the public or national security. Offences that may result in consideration for category A or restricted status include: (attempted) murder, manslaughter, wounding with intent, rape, Indecent assault, robbery or conspiracy to rob (with firearms), firearms offences, importing or supplying Class A controlled drugs, possessing or supplying explosives, offences connected with terrorism and offences under the Official Secrets Act.
B) Those who do not require maximum security, but for whom escape still needs to be made very difficult.
C) Those who cannot be trusted in open conditions but who are unlikely to try to escape.
D) The above are all closed prisons. D are open prisons. Those who can be reasonably trusted not to try to escape, and are given the privilege of an open prison. Prisoners at "D Cat." (as it is commonly known) prisons, are, subject to approval, given ROTL (Release On Temporary Licence) to work in the community or to go on "home leave" once they have passed their FLED (Full Licence Eligibility Dates), which is usually a quarter of the way through the sentence.
Category A prisoners are further divided into Standard Risk, High Risk, and Exceptional Risk, based on their likelihood of escaping.
Men on remand are held in Category B conditions with the exception of some of those who are held to be tried on (very) serious offences. These men are held in "Provisional Category A" conditions.
Women are also classified into four categories. These categories are:
Restricted Status is similar to Category A for men.
Closed is for women who do not require Restricted Status, but for whom escape needs to be very difficult.
Semi-open was introduced in 2001 and is for those who are unlikely to try to escape, but cannot be trusted in an open prison, but it appears that this is being phased out as HMP Morton Hall and HMP Drake Hall were re-designated as closed in March 2009.
Open is for those who can be safely trusted to stay within the prison.
Remand prisoners are always held in closed prisons.
When young people under the age of 21 are sentenced or remanded to custody, they may be sent to one of four types of establishment depending on their needs, age and the nature of the offence of which they have been accused or convicted:
Secure Training Centres (STCs): privately run, education-focused centres for detained boys and girls aged between 12 and 17.
Secure Children’s Homes (SCHs): run by local authority children's services, and one charity provider, these are focused on meeting the physical, mental, emotional and behavioural needs of vulnerable detained boys and girls aged between 10 and 17. Not all children detained in SCHs have necessarily been convicted of crimes as such, some are detained under the Children Act 1989 due to reasons such as their high risk of vulnerability to abuse, drugs and prostitution, the danger they pose to themselves or others, or because of their history of absconding from less secure accommodation, such as regular non-secure children's homes.
Youth Offender Institutions (YOIs): run mainly by HM prison service and some private companies, these accommodate only boys aged 15 to 17 who have been convicted or remanded. They are generally more "prison"-based and focus less on the health and educational needs of those detained on site with lower ratios of staff to prisoners compared to STCs and SCHs. These establishments work and run almost identical to YOIs apart from the fact they only accommodate younger boys aged 15 to 17. Girls aged 15 to 17 are not held in YOIs, instead they are held at either STCs, SCHs or in female YOIs in separate areas to the older females.
Her Majesty's Young Offender Institution (YOIs) – run mainly by HM prison service and some private companies, these accommodate young men and women from the age of 18 up to their 21st birthday who have been convicted or remanded. They are generally more prison" based and focus less on the health and educational needs of those detained on site with lower ratios of staff to prisoners compared to STCs and SCHs. These establishments work and run almost identical to adult prisons apart from the fact they only accommodate younger adults aged 18 to 21.