Ralph Kimball the co-founder of the data warehousing concept has defined the data warehouse as a "a copy of transaction data specifically structured for query and analysis".
Data warehousing is closely linked to OLAP - Online Analytical Processing - which relates to complex analysis of (usually aggregated, or denormalized) data in a data warehouse.
In contrast, OLTP refers to Online Transaction Processing. An OLTP database is used for day-to-day business operations and is therefore well-normalized.
Introduction (from Wikipedia)
A data warehouse is a repository (collection of resources that can be accessed to retrieve information) of an organizatioan's electronically stored data, designed to facilitate reporting and analysis. More simply, a data warehouse is a collection of
Online transaction processing, or OLTP, refers to a class of systems that facilitate and manage transaction-oriented applications, typically for data entry and retrieval transaction processing. The term is somewhat ambiguous; some understand a "trans