Currently, there are four main types of consulting firms: 

1. Large, diversified organizations that offer a range of services, including information technology consulting, in addition to a strategy consulting practice (e.g. Accenture, ABeam Consulting, Capgemini, Cognizant, Deloitte, IBM, Logica, PA Consulting). Some very large IT service providers have moved into consultancy as well and are also developing strategy practices (e.g. Wipro, Tata Consultancy Services, Infosys) 
2. Medium-sized information technology consultancies, that blend boutique style with some of the same services and technologies bigger players offer their clients. 
3. Management and strategic consulting specialists that offer primarily Strategy Consulting and Business Intelligence Models to any industries (e.g. Oliver Wyman, Bain & Company, Booz & Company, McKinsey & Company, Arthur D. Little and The Boston Consulting Group). 
4. Boutique firms, often quite small, which have focused areas of consulting expertise in specific industries, functional areas or technologies. Most of the boutiques were founded by famous business theorists. Small firms with fewer than 50 employees are often referred to as niche consultancies (e.g. Insight CP in the USA, iProCon Ltd. in the UK, R2P GmbH in Germany, Six Sigma Center of Excellence - SSCX in Indonesia), who help keep prices down and sometimes introduce new ideas emulated by larger competitors. If they have a unique concept and market it successfully, they often grow out of this segment very fast or are bought by larger players interested in their know-how.(e.g. Tecnova India Pvt.Ltd.,Visnova, CPL Business Consultants)