上班

Use it as a verb. You can say 我去上班 to mean 'I am going to work.' You can also use it to ask about schedules. For example, 'What time do you 上班?' It is a very flexible term. You do not need fancy grammar to make it work. Just drop it after the subject. It is like a multi-tool for your daily routine.

Use this every single day. Use it when you are leaving the house. Use it when talking to your boss about your hours. It is perfect for texting friends to explain why you are busy. If you have a job, you will use this word. It is the most common way to describe your professional activity.

Do not use it for school or classes. Students do not 上班; they 上课. Also, do not use it for chores at home. It implies a formal job or a shift. If you are a freelancer working at a cafe, you might say it. But if you are just cleaning your room, skip it. It sounds too 'corporate' for doing the dishes.

The 'Up' in 上班 has historical roots. In ancient Chinese courts, officials literally 'went up' to the hall to see the Emperor. Today, it reflects the structure of the workday. There is a counterpart called 下班, which means 'to finish work.' The workday is a cycle of going 'up' and coming 'down.' It shows how deeply work is integrated into the daily rhythm of life.

You will often hear 加班. This means 'to work overtime.' It is a very common (and sometimes sad) part of life. Another one is 上班族. This refers to 'office workers' or 'salarymen.' If you take the subway at 8 AM, you are surrounded by the 上班族. It is a whole subculture of commuters and coffee drinkers.