Granting someone power of attorney allows them to make decisions for you. Power of attorney is a relatively simple and inexpensive procedure. It's possible to grant power of attorney for your financial affairs to one person and power of attorney for your medical decisions to another person. Of course, you can always have one person do both.
When you give someone power of attorney for your finances, you allow that person to manage your bank accounts, house, and any other assets you may have. If you have joint accounts with another person (your spouse, partner, or a parent, for example), that person can probably manage your finances without power of attorney. Still, if you have any accounts that are only in your name, power of attorney may be necessary.
Giving someone power of attorney for your healthcare allows that person to make choices for your care. Talk to this person and other loved ones about what type of medical treatment you want and don't want if you're unable to make decisions for yourself.
Think about who you might want to make decisions for you if you can't make them. If you decide you want to grant someone power of attorney for finance and healthcare, talk to an attorney so the proper documents can be prepared. Granting or revoking power of attorney must comply with state laws to be valid, so you want to be sure everything is done properly.