What vetoes are
A veto is when the President rejects a bill passed by Congress; Congress can try to override a veto with a supermajority.
Plain-language explanation
A veto is when the President rejects a bill passed by Congress; Congress can try to override a veto with a supermajority.
Example
The President may veto a bill and explain concerns; Congress can return the bill with changes or attempt an override.
Why it matters
Vetoes are part of checks and balances between branches of government.