Franklin Roosevelt broke the precedent set by Washington of only serving two terms when he ran for a third and then a fourth term. He was the only president to ever run for a third term .
he served two terms
George Washington served two terms.
Frank Roosevelt
George Washington, the first U.S. president, set the precedent of retiring after two terms in office. His example was followed until Franklin D. Roosevelt broke it, serving three full terms and part of a fourth term before his death. After his death, Congress decided to make Washington's precedent law in order to prevent a president from becoming too powerful, as some saw FDR to be, and undermining the checks and balances built into our system.
he made an agreement to serve two terms
He felt he had he had done his share by serving two terms and was ready to go home and run his plantation. Also, he felt that it would set a bad precedent for the future if he served any more terms. He strongly believed that the presidency should not be a life-time or long-term job.
He served two terms: 1789-1793 and 1793-1797
I am not sure how important it was since there were not really very many presidents who would have served a third term even without Washington's precedent. Maybe Jefferson, Madison, Monroe or Theodore Roosevelt would have considered a third term had the precedent not been set against it. Jackson and Wilson might have if they were healthier when their second terms ended.
George Washington set the precedent by voluntarily stepping down after serving two terms as President of the United States. He did not seek a third term, establishing the tradition of a two-term limit for the presidency that was eventually codified into law through the 22nd Amendment to the U.S. Constitution.
One of the first presidential precedents set by George Washington was the two-term limit. Despite being popular enough to be elected for a third term, Washington voluntarily stepped down after serving two terms, setting a precedent that subsequent presidents followed until it became an established rule with the 22nd Amendment in 1951.
Precedent, in legal terms, is the decision of judges in similar court cases to yours. If there is a previous case that is similar with a decision, the judge must follow the precedent unless the facts are distinguishable.