Consulting firms are professional service firms that provide expertise and specialized labor for a fee, through the use of consultants. They offer professional advice, guidance, and actionable solutions to businesses experiencing issues they can’t deal with in-house. Consulting firms tend to have specific focuses, and companies pay them to lend their expertise on problems that can’t be handled internally. Consulting firms provide feedback and actionable strategies to companies to improve their efficiency or solve complex problems in a specific area. The leading consulting firms have built up critical expertise in key areas such as pricing, marketing, organizational behavior, post-merger integration, etc. . Consulting firms may be brought on to provide an objective, third-party opinion on a major decision a company is making. Consulting firms sell projects to clients, each of which lasts a few months, and aims to diagnose/solve one specific problem for the client business or organization. Consulting firms may or may not be involved in the implementation of the solutions in a follow-up project. Consulting services are part of the professional services and account for several hundred billion dollars in annual revenues.