There were few agreed-upon standards. With the introduction of the personal computer, a requirement for interconnecting various computers became evident. A set of networking standards did not mean that all existing network schemes would go away, but that a common denominator was needed to facilitate the interconnection of incompatible systems. Today, most hardware manufacturers and software developers rely on standards to ensure that their products will interoperate with one another. A product that is not based on standards is known as a proprietary product.
Proprietary products are typically only available from one company.
It's best to avoid using proprietary products if you can. The history of the computer industry suggests that the vendors of proprietary systems tend to do poorly in the market and often do not survive. In the worst case this could leave you with a network with few or no available parts. Generally a network that relies heavily on proprietary products is likely to be more expensive to support and less flexible. Realize that many companies will still try to sell you proprietary solutions to your networking problems.