A kidney transplant may be needed because of disease or damage that prevents a person's own kidneys from working effectively.
During a kidney transplant, one of a person's own kidneys is replaced with one from a live or deceased donor.
Until a donor kidney is available, the work of the kidneys in filtering waste from blood and processing urine is done with a kidney dialysis machine.
The decision on whether a kidney transplant is appropriate will depend on factors including the person's overall health, whether doctors assess a good chance of success from the operation and whether the recipient will comply with all the post-operation requirements, including taking anti-organ rejection drugs and attending follow-up appointments.
The NHS says that for kidney failure, around 1 in 3 patients are suitable for a transplant.
We have two kidneys, but the body can work with just one. That's why live kidney donation is possible, usually from a close relative who is a match for a transplant.
Around 3,000 kidney transplants are carried out each year in the UK, with a waiting list of around 5,000 or more people.
A system is in place to prioritise patients, with children and young adults usually first as they will get the most benefit from the organ over their lifetime. A scoring system is in place to prioritise adults needing a kidney transplant.
Once a person is accepted for a kidney transplant, they will need to be on standby around the clock to be ready to go to a specialist transplant centre whenever a suitable kidney becomes available.
After a kidney transplant, people will be advised to lead as healthy a lifestyle as possible, with a good diet, managing weight, avoiding infections and not smoking.
In some cases, a transplanted kidney can fail and a person will usually go back on the waiting list.
A number of factors affect how long a transplanted kidney will last, including whether it was from a living or deceased donor and the closeness of the organ matching the recipient's blood group and tissue type.
Around 95% of transplanted kidneys last a year, up to 90% last 5 years, and around 75% last 10 years.