A data mart is a subset of a data warehouse that is designed to answer a specific question, serve a specific department, business unit, or line of business within an organization. It provides a more focused view of an organization's data, tailored to meet the specific needs of a particular group. Data marts contain only the data that is relevant to a specific business unit, and can be created and managed independently of the main data warehouse.

Data marts are often used to address performance and scalability issues in large data warehouses. By breaking down a large data warehouse into smaller, more manageable pieces, data marts can help organizations more easily manage and analyze their data, while also providing a more focused view of the data that is most relevant to each business unit.

In summary, a data mart is a subset of a data warehouse that provides a tailored view of an organization's data for a specific department, business unit, or line of business, helping to improve performance, scalability, and the ability to derive meaningful insights from the data.

A data mart matters because it provides organizations with a focused and tailored view of their data, specifically designed to meet the needs of a particular department, business unit, or line of business.

The following are some of the key benefits of using a data mart:

• Improved performance:
  Data marts are smaller and more focused than data warehouses, and are therefore faster and more efficient when it comes to querying and analyzing data.
• Better user experience:
  Data marts provide a more focused view of the data, making it easier for users to find the data they need and generate insights that are relevant to their specific business unit.
• Increased agility:
  Data marts can be created and managed independently of the main data warehouse, allowing organizations to quickly respond to changing business needs and implement new data sources.
• Improved data governance:
  Data marts can help organizations improve data governance by providing a clear definition of what data is included in each mart, making it easier to manage and maintain data quality.
• Improved data security:
  Data marts can help organizations improve data security by providing a more focused view of the data, making it easier to control access and enforce data privacy policies.

Overall, a data mart provides organizations with a valuable tool for managing and analyzing their data, enabling them to make better-informed decisions and drive business outcomes.