Time series is one of the most common ways to find data in the real world. A time series is defined as the changes of a variable through the time. Time series analysis (TSA) is widely used in economics, weather, and epidemiology. Working with time series needs to define some basic concepts of trend, seasonality, and noise.
In the following figure, found at http://www.gold.org/investment/statistics/gold_price_chart/, we can see the time series for gold price in US since July 2010.
Typically the easiest way to explore a time series is with a line chart. With the help of direct appreciation of the time series visualization, we can find anomalies and complex behavior in the data.
We have two kinds of time series; linear and nonlinear. In the following figure, we can see an example of each one. Plotting time series data is very similar to scatterplot or line chart, but the data points in X axis are times or dates: