A power of attorney is a legal document that gives someone you name the legal authority to make decisions on your behalf. Generally, they are especially useful in the event of incapacity, which is when you cannot make or communicate decisions on your own.
A power of attorney allows you to appoint a surrogate decision maker for health care, medical treatment and financial decisions. Signing one does not mean that you are surrendering your authority to make these decisions for yourself. It simply means that someone else is allowed to do so as well, or in your place, if you are unable.
A power of attorney is important to have in place so that you can avoid the expensive and public guardianship process. If you were to become incapacitated without authorizing an agent to make decisions for you, the court would need to appoint a guardian to make decisions on your behalf. A guardianship is not ideal for most people because can result in a loss of control and the appointment of an unwanted stranger as your surrogate decision maker.