In the United States, a budget resolution is legislation in the form of a concurrent resolution setting forth the congressional budget. The budget resolution establishes various budget tools, divides spending totals into functional categories (e.g., transportation), and may include budget reconciliation instructions to designated House or Senate committees.
The main purpose of the budget resolution is to provide spending targets for the House and Senate appropriation subcommittees. Over time, advocates for spending in particular areas are appointed as members of the relevant appropriation subcommittees. Appropriation Committee members are also visited by many lobbyists encouraging spending on particular programs. (Spending advocates tend to donate campaign funds to the members of the relevant appropriations subcommittee.) So, over time, appropriation subcommittees have tended to add programs and spending to the President's proposed budget rather than working to reduce spending. If both houses of Congress pass a budget resolution before the appropriation subcommittees begin their work, the subcommittees will have a spending level target from their colleagues as well as from the President. However, in recent years, the House and the Senate could not agree on spending levels, so each subcommittee wrote its appropriation bill using its own discretion about the spending in its area, and any difference between the House and the Senate had to be resolved in a Conference Committee. In such situations, spending authority is granted by continuing resolution rather than the Budget process as prescribed by law in the Budget Act of 1974.
The Budget Committee in the House and the Senate receive the President's budget proposal for the next fiscal year. That proposal specifies federal spending on a detailed level. Each budget committee holds hearings on the budget and then votes out a Budget resolution, which may contain spending details that are different from those in the President's budget. The same Budget Resolution must be adopted by both the House and the Senate to be binding on that year's budget process. The President's budget together with the Budget resolution then go to each appropriation subcommittee for a detailed review. Each subcommittee in the House and the Senate drafts an appropriation bill for a functional category of the government which tells how federal funds should be spent in that area. The government operates only when Congress has passed an appropriations bill and the President signs it into law or the President's veto has been overturned.
-  US Senate Reference