An ontology is a formal way to categorize things.  We all encounter ontologies in our daily lives, for example:

• Reading the names of the isles at a grocery store [Bread, Dairy, Meat, ...]
• Determining what folder to save a work document [Reports, Models, Contracts, ...]
• Organizing your closet [Suitcases, Shirts, Shoes, ...]

In the IT services market, there are three important ontological classes that stakeholders want to view market data by:

• Services Markets [Plan/Build/Run by Infra/Apps/Business Processes]
• Geographies [Americas, EMEA, AP]
• Industries [Financial Services, Communications/Media/Technology, Health & Public Sector, Retail, Manufacturing, Resources]