Appropriations
The legislation that actually provides money to federal agencies, distinct from the authorisation that permits a programme to exist.
Federal spending takes two separate acts of Congress and conflating them is the most common misreading of a budget story. An authorisation creates a programme and sets a ceiling on what it may receive. An appropriation provides the money. A programme can be authorised at a large number and appropriated nothing, in which case it exists on paper and does nothing in practice.
Appropriations run on the federal fiscal year, which begins on 1 October. When the bills are not passed in time, the alternatives are a continuing resolution or a lapse in funding.
What the federal government did, once a day.
One email each weekday: the rules, filings, votes and Fed decisions that actually changed something, each one linked to the document it came from.