Data analysis tools like Excel and Tableau have made it easy for users to maintain live connections to databases.
In order to work with data, it typically has to first be extracted, which means accessing or connecting to the data. When data is stored in a relational database, you will often need to extract relevant data from the database and analyze it in Excel or Tableau.
Sometimes extracted data isn't formatted in the manner it needs to be for analyses. In these cases, the data needs to be transformed - cleaning the data (e.g., removing rows or columns that have blank or erroneous values), sorting the data, and or filtering the data.
The final step, loading, ensures that after the data has been transformed, you have loaded it into an appropriate data analysis tool (e.g., Excel or Tableau).