A data warehouse is a collection of all the digital information of an organization that can be used for decision making. Data warehouses contain core operational and analytical data from multiple sources, such as transactional databases, web logs, marketing campaigns, customer feedback surveys, social media data and more. In other words, a data warehouse is the foundation upon which organizations can make informed decisions.

Data warehouses contain many functions that help to form the basis of business processes and activities. These functions are divided into three categories: querying, extracting, and loading (ETL). Querying allows users to quickly and efficiently parse through large amounts of data in order to gain insights. Extracting provides tools to extract data from various types of sources, such as file systems and databases. Loading enables the importation of data into the data warehouse for further analysis.

Overall, the purpose of a data warehouse is to provide an efficient platform for organizations to store, analyze and query data for their business needs. With the use of its many functions, a data warehouse can enable businesses to better understand their customers, optimize performance, improve profits and enhance their products or services.