ERP is Online Transaction Processing (OLTP) software

A transactions in one module could start coordinated transactions in other modules.   

For example:-
when shipping dock clerk records the transaction that goods have shipped to a customer,
related changes are made in other modules: order management, billing, and inventory systems.  

New transactions for revenue recognition and cost of goods sold are started

About OLTP

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 "transaction" in the context of computer or database transactions, while others (such as the Transaction Processing Performance Council) define it in terms of business or commercial transactions. OLTP has also been used to refer to processing in which the system responds immediately to user requests. An automatic teller machine (ATM) for a bank is an example of a commercial transaction processing application.

The technology is used in a number of industries, including banking, airlines, mailorder, supermarkets, and manufacturing. Applications include electronic banking, order processing, employee time clock systems, e-commerce, and eTrading. The most widely used OLTP system is probably IBM's CICS.

OLTP Requirements

Online transaction processing increasingly requires support for transactions that span a network and may include more than one company. For this reason, new OLTP software uses client/server processing and brokering software that allows transactions to run on different computer platforms in a network.

In large applications, efficient OLTP may depend on sophisticated transaction management software (such as CICS) and/or database optimization tactics to facilitate the processing of large numbers of concurrent updates to an OLTP-oriented database.

For even more demanding decentralized database systems, OLTP brokering programs can distribute transaction processing among multiple computers on a network. OLTP is often integrated into SOA service-oriented architecture and Web services. Because there is a need for transactions you will need online processing.

Benefits Of OLTP

Online Transaction Processing has two key benefits: simplicity and efficiency. Reduced paper trails and the faster, more accurate forecasts for revenues and expenses are both examples of how OLTP makes things simpler for businesses.

Next :
14. ERP AS Application Service Providers (ASP)

16. Advantages of the ASP model ( Business On-Line)

17. Disadvantages of ASP Model (Business On-Line)