Combining Data with Pandas - Merge - Inner, Outer, Left and Right joins

If we assume that there is a relationship between two or more independent variables and one dependent variable, we can develop a model to predict the value of the dependent variable, given a set of values of the independent variables.
For example, if we have a dataset that contains the following data:
Sales Price Advertising expenditure We can assume that Sales is the dependent variable, while Price and Advertising Expenditure are the independent variables because the price and the advertising expenditure are directly controlled by the supplier of a product or service.