The majority of businesses do not stay open seven days a week. Instead, they opt to be open only a set number of pre-designated business days. In general, a work week is made up of five business days — Monday, Tuesday, Wednesday, Thursday and Friday — although some companies may consider every day a business day, or may only take one day off a year. Certain holidays are not business days. Generally, if a company does not require employees to work on a given holiday, the company does not consider it a business day. For all intents and purposes, when a company refers to a "business day," it is referring to the typical workweek composed of Monday through Friday.

Whether a day is considered a business day can also depend on location. In the United States, as well as Europe, generally Saturday and Sunday are not considered business days. However, in Israel and some Muslim countries, Sunday is a business day, but Friday is not.

A business day has become a standard unit of time in the business world: if a person is determining the length of time needed to deliver a package or complete a project, he will list time requirements in business days to make it clear that weekends should not be included in any figures. The business day unit is especially useful to the shipping and banking industries, who must predict availability of items and money for their customers. Human resources departments also use business days as a unit of measurement for determining length of employment and eligibility for benefits for employees.

The length of a single business day is not set. Instead, as each company sets its own operating hours, they set the length of their business day. Some companies maintain schedules with twenty-four hour days.

The concept of a business day has been challenged by many employees over the past few years, as many employers have allowed employees to switch to more flexible schedules. Especially for those individuals whose work is based online, there is very little difference between a business day and a weekend.