Authorization is, in government, a statutory provision that obligates funding for a program or agency. An authorization may be effective for one year, a fixed number of years, or an indefinite period. An authorization may be for a definite amount of money or for "such sums as may be necessary."
The formal federal spending process consists of two sequential steps: authorization and then appropriation. At state and local levels, authorization and appropriation are often combined at the beginning of the fiscal year as passage of the annual budget also serves as the appropriation act, though during the year additional authorizations (and appropriations) are commonly made (such as if a new fire station is opened, the government will authorize and appropriate funds to operate it).
-  US Senate Reference