Center For Civic Education
60 Second Civics: How Congress Functions: Pt. 20: Vetoes and Overrides
Even when a bill is passed by Congress, it still must be signed by the President, who may decide to veto it. If this happens, Congress can also override that veto through a new vote in both chambers.
Center For Civic Education
60 Second Civics: Role of President Pt. 9: Jackson and the Modern Presidency
While in office, Andrew Jackson made more use of his veto power than all other presidents combined before him. This gave rise to a much more powerful presidency.