Ratified: Feb 27, 1951
Section 1: No person shall be elected to the office of President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of President more than once. But this Article shall not apply to any person holding the office of President when this Article was proposed by Congress, and shall not prevent any person who may be holding the office of President, or acting as President, during the term within which this Article becomes operative from holding the office of President or acting as President during the remainder of such term.
The origination Constitution set on term limits on the President. Franklin D. Roosevelt was elected to office 4 times in a row, serving over 10 years (1933-1945). Some historians believe he would have won another time if he had not died in 1945. Some people however, believed that it is unhealthy for the country to have a President in office for that long. The 22nd Amendment was proposed, passed by Congress, and ratified by the states limiting a President to 2 terms. Also, limiting the President to 1 term of his own if he serves 2 or more years of another Presidents term.
Section 2: The article shall be inoperative unless it shall have been ratified as an amendment to the Constitution by the legislatures of three-fourths of the several States within seven years from the date of it submission to the States by the Congress.
Pretty self explanatory.