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In online transaction processing (OLTP), information systems typically facilitate and manage transaction-oriented applications. This is contrasted with online analytical processing.

The term "transaction" can have two different meanings, both of which might apply: in the realm of computers or database transactions it denotes an atomic change of state, whereas in the realm of business or finance, the term typically denotes an exchange of economic entities (as used by, e.g., Transaction Processing Performance Council or commercial transactions.): 50  OLTP may use transactions of the first type to record transactions of the second.

OLTP has also been used to refer to processing in which the system responds immediately to user requests. An automated teller machine (ATM) for a bank is an example of a commercial transaction processing application. Online transaction processing applications have high throughput and are insert- or update-intensive in database management. These applications are used concurrently by hundreds of users. The key goals of OLTP applications are availability, speed, concurrency and recoverability (durability). Reduced paper trails and the faster, more accurate forecast for revenues and expenses are both examples of how OLTP makes things simpler for businesses. However, like many modern online information technology solutions, some systems require offline maintenance, which further affects the cost-benefit analysis of an online transaction processing system.

OLTP is typically contrasted to OLAP (online analytical processing), which is generally characterized by much more complex queries, in a smaller volume, for the purpose of business intelligence or reporting rather than to process transactions. Whereas OLTP systems process all kinds of queries (read, insert, update and delete), OLAP is generally optimized for read only and might not even support other kinds of queries. OLTP also operates differently from batch processing and grid computing.: 15 

In addition, OLTP is often contrasted to OLEP (online event processing), which is based on distributed event logs to offer strong consistency in large-scale heterogeneous systems. Whereas OLTP is associated with short atomic transactions, OLEP allows for more flexible distribution patterns and higher scalability, but with increased latency and without guaranteed upper bound to the processing time.
Based on the below Wikipedia content, what is OLTP?
OLTP stands for "online transaction processing" and refers to information systems that process transactional data. The applications generating such data often require a high volume of transactions -- such as being used concurrently by hundreds of users. An example of a commercial transaction processing application is an automated teller machine (ATM). OLTP is often contrasted with OLAP (online analytical processing) which is typically characterized by more complex queries but with much smaller volume (for example, for business intelligence reporting).