Business quarters, also known as fiscal quarters, are the four three-month segments that constitute a company's fiscal year. Fiscal quarters are expressed with "Q" followed by the relevant number and year. The second quarter for the 2014 fiscal year is expressed as Q2 2014.
While some companies align their fiscal years with the calendar year, some do not. This means that Q1 does not necessarily begin on Jan. 1 for all companies. As an example, the fiscal year for the U.S. government starts in October. That means that Q1 for the federal government starts on Oct. 1 and Q4 ends on Sept. 30. Fiscal quarters are used for reporting financial information to investors as well as for tax and other filings to government agencies.