From the Document: "The budget reconciliation process [hyperlink] is an optional, expedited legislative process provided under the Congressional Budget Act of 1974, as amended (P.L. 93-344; the Budget Act). It consists of several different stages, beginning with the adoption of the budget resolution. The purpose of the reconciliation process is to allow Congress to use special procedures when considering legislation that would bring existing budgetary laws into compliance with the fiscal policies that Congress establishes in the annual budget resolution. If Congress intends to use this process, reconciliation directives (also referred to as reconciliation instructions) must be included in the annual budget resolution. These directives trigger the second stage of the process by instructing individual committees to develop and report legislation that would change laws within their respective jurisdictions related to direct spending, revenue, or the debt limit. Once a specified committee develops legislation in response to a reconciliation directive, that legislation is eligible to be considered under expedited procedures in both the House and the Senate. These procedures are especially important in the Senate, as they include a 20-hour limit on debate time and therefore mean that reconciliation legislation does not require the support of three-fifths of all Senators to bring debate to a close."
CRS Insight, IN11681
Congressional Research Service: https://crsreports.congress.gov/