Let's start with some fundamental questions: 

• In our company, WHY are we doing the things that we do?
• What should our business do (or start doing) to be(come) successful?

When trying to answer these questions, Business Capabilities are the key:

• a business can be seen as a collection of capabilities
• capabilities define WHAT a business does or needs to be able to do to be successful
• important here is that each business capability is independent from the other

Now that we kind of know what a business capability is, different types can be distinguished:

• CORE capabilities are the capabilities that cannot be imitated by other companies/businesses and therefore define what competitively distinguish a company from its competitors
• SUPPLEMENTAL capabilities add value to the core capabilities but can be imitated by other businesses
• ENABLING capabilities are necessary but not sufficient to competitively distinguish a company

Defining Business Capabilities is an exercise that is best done via workshops involving different kinds of people: operational/business, strategy and management. When business capabilities are defined/listed, they can be brought together/organised into a business capability map. This is a hierarchical structure of the capabilities the business needs (or will be needing) to create business value. This map can also be used to discover high-/low-priority business capabilities.

The business capability map can also be linked to the IT Application landscape: several applications can be mapped to one specific business capability or one application can be used to support multiple business capabilities.

The Business Capability Map also offers a means to understand which business capabilities are (not) supported by the IT applications and where future investments should be made. If a business capability is not/badly supported by IT systems, measures can be taken. The business capability map can also be a means of transforming the business/IT landscape or to get a better alignment between business needs and IT needs. Furthermore, it can also link the business processes to the capability map so that you can easily navigate from a business capability (what) to the operational processes (how).