The purchasing (procurement) process consists of several steps that can be viewed in terms of pre-purchase, purchase consummation, and post-purchase activities (see figure). In the pre-purchase activities, the users browse through various sites, compare prices, and select the online-merchants they want to buy the goods from. Naturally, the Web and the Internet have had the most profound impact on these activities. In the purchase consummation activities, also known as order fulfillment, the user may use a shopping cart and place an order by using a payment system. Naturally, the e-commerce payment systems play an important role in this area. The post purchase activities involve the classical "back-end" systems that handle payment settling, shipping and receiving, etc. Many of these applications are legacy applications that have been around since the 1970s and 1980s.
 

Order fulfillment is the main process of purchasing. The order can be fulfilled by a local inventory of the enterprise, a virtual inventory between various trading partners, or an e-marketplace.

Online Purchasing is at the core of E-commerce .It allows the users to select merchants, place orders for needed items online, make payments online, track the order online, and enter trouble tickets online.