From Wikipedia

In statistics and econometrics, panel data or longitudinal data^[1][2] are multi-dimensional data involving measurements over time. Panel data contain observations of multiple phenomena obtained over multiple time periods for the same firms or individuals

Time series and cross-sectional data can be thought of as special cases of panel data that are in one dimension only (one panel member or individual for the former, one time point for the latter).

A study that uses panel data is called a longitudinal study or panel study.

 

Cross sectional data:

Cross-sectional data, or a cross section of a study population, in statistics and econometrics is a type of data collected by observing many subjects (such as individuals, firms, countries, or regions) at the same point of time, or without regard to differences in time.

Analysis of cross-sectional data usually consists of comparing the differences among the subjects.

 

Examples

 

Panel Data

Cross Sectional Data

Time Series