Time Series Analysis (TSA) is a statistical method that is slowly spreading in psychological research. Since it can be a very complex topic, this paper is an introduction that aims to explain the main concepts of TSA in the simplest possible way, facilitating the subsequent learning process. The article generally outlines the intensive longitudinal data (ILD), the components of a Time Series, the possible operations that can be done on this type of data, and the most common models to explain and predict the change of one or more variables over time.