A joint resolution which continues in effect appropriations legislation for specific ongoing activities of federal departments or agencies when a fiscal year begins and Congress has not yet enacted all of the 13 regular appropriations bills for that fiscal year.
When Congress cannot resolve the next fiscal year's budget by the start of the fiscal year (October 1st), it typically votes for a continuing resolution which provides appropriations for the continued functioning of government. The level of appropriations is generally at the level of the past fiscal year, but may include exceptions if so decided by Congress.
If Congress has not enacted all the necessary appropriations bills when a fiscal year begins, it passes a joint resolution continuing appropriations to fund the government until the appropriations bills can be enacted into law.