What essential step is required before building custom dashboards and reports in Power BI?

The essential step required before building custom dashboards and reports in Power BI is connecting Power BI to the relevant data sources. This involves selecting the appropriate connector for each data source, providing the necessary credentials, and importing the data into Power BI. Power BI supports a wide range of data sources, including databases, spreadsheets, cloud services, and web APIs. Before you can create visualizations and perform analyses, you need to establish a connection to the data you want to work with. This connection allows Power BI to retrieve and refresh the data automatically. After connecting to the data sources, it may also be necessary to clean, transform, and model the data to ensure its accuracy and consistency. This process involves removing errors, handling missing values, and creating relationships between different tables of data. Once the data is properly connected and prepared, you can then begin building custom dashboards and reports using Power BI's visualization and analysis tools.