A Power of Attorney (POA) names an agent and a successor agent (if desired) to handle various financial matters for you, as the principal.
A POA can be used for only a specific financial transaction, such as allowing someone else to handle a real estate closing for you.
A POA can also be used to make sure there is someone available to handle your financial affairs in the event you later become incapacitated. So long as the POA is signed while you have capacity, it can still be used after you lose capacity. A POA, combined with a Health Care Proxy, can avoid the necessity of having an Article 81 guardian appointed for you if you become incapacitated later in life.
A gift rider can also be added to a POA. That allows your agent to give gifts to certain people within certain limits. This option should be carefully considered after discussion with your attorney.