A time-series data shows information about the same subject or element of a sample or population for different periods of time.
The information below is not based on real statistical data, but it can help us understand what we mean by time-series data.
As you can see, the information is about the same subject that is numbers of cars rented by Alamo.
Furthermore, the information is given for different time period. Notice that a time-series data could also be compiled by using month as a time frame instead of year.
For instance, you could compile information from January to December.
In summary, a set of data is a time-series data whenever the following two conditions are met.