January, February and March are the months that make up the first quarter if an organization's fiscal year starts at the beginning of January. Different organizations may start their fiscal years at different times, though, and the first three months of that time period would make up the first quarter. In the business and government sectors in the United States, a year is divided up into four pieces, each of which is called a quarter. This is done so that analysts, accountants, independent contractors, investors, tax regulators and other interested parties can easily track growth, profits, goals and set due dates for certain regulatory items.
Given that there are 12 months in a year, a quarter consists of 3 months. Different organizations have different objectives for each quarter of the year. Company analysts will often compare the same quarter in different years to observe growth or success over time with seasonal effects minimized. Companies must also report financial statements and other operating information in their 10-Q reports to the SEC at the end of each quarter.
Some people may have to pay income tax to the federal government on a quarterly basis, as well. For example, independent contractors and freelancers may be required to pay estimated taxes on their income each quarter to account for federal tax liability.