Time series is a way of looking at how something changes over a period of time. It can be used to track things like the amount of money in a bank account or how hot it gets outside every day. It can also show how a stock or a company changes over time. The "time" part looks at how things change over a certain amount of time like a day, a week, a month, a year and so on. The "series" part shows the different changes that happen like how a bank account goes up and down over time.