In many Western cultures, particularly American culture, taking a day off (especially a sick day) can be framed as asserting a right. An employee might say, “I'm taking a sick day today.” The focus is on the individual's entitlement. In Chinese culture, the process is framed differently due to traditional values of hierarchy, respect for authority, and collectivism. 请假 (qǐngjià) is a formal request made to a superior, not a declaration. By using this term, you are acknowledging your role within the group (the company, the class) and showing respect for your boss's or teacher's authority to manage the team's resources—including your time. This act reinforces group harmony. Instead of simply disappearing and causing disruption, you are formally explaining your absence and seeking approval, allowing the leader to plan accordingly. Failing to 请假 and simply not showing up is a serious offense called 旷工 (kuànggōng) for work or 旷课 (kuàngkè) for school, which shows great disrespect.
请假 is a high-frequency term used in daily professional and academic life.