There is now essentially no business that operates without technology, specifically computers. Nearly every business, from major corporations to small town hair salons, uses computers to attract clients, sell products, manage inventory, keep track of data, handle their books, and on and on.
Obviosuly the scale of this technology need depends on the type and size of the business. Online-only businesses often use the internet to try and replace real estate and employees and thus keep costs down--they are wholly reliant on technology. Larger online businesses need huge farms of servers to handle the amount of traffic that visits them and to keep track of the massive date they collect. To manage all of this, they will contract with data management companies like Oracle to use their software and support to keep this business running smoothly. Smaller companies might have a local web hosting service and a small website with basic business information on a web page--essentially a business card that is virtual.
In the bricks and mortar businesses, computers will often handle all data related tasks and also the marketing for the smaller companies (print letters, brochures, post ads, etc). The larger companies try to offer the same services in store and online so they will essentially have two companies: one online and one physical that do the same things and intergrate their computer systems.