With respect to their relationship to custom technology, there are three kinds of companies.

1. Tech is the product. These are companies that sell or license software, technology to their customers. This includes Apple, Microsoft, Oracle, and most consumer electronics companies.
2. Tech drives the product. These are companies for whom technology is so integral to what they deliver that they have software development in-house. This includes almost all web businesses, but also oil drilling, pharmaceuticals, and other R&D-heavy business.
3. Tech is a vendor. These are companies that probably never speak directly to a technologist at all. They work with integration vendors and IT people to get the tools they need for their business. This includes advertising agencies, hospitals, and businesses in almost all service industries.

The really interesting cases are the cross-overs, like Amazon, which has moved in the past few years with its increasing AWS presence to now straddle types 1 and 2.