Professional services firms exist in many different industries. They include lawyers, advertising professionals, architects, accountants, financial advisers, engineers, and consultants, among others. Basically, they can be any organization or profession that offers customized, knowledge-based services to clients.

In his influential book "Managing the Professional Service Firm," David Maister compares the professional services organization to a medieval craftsman's shop. Today, just as in the Middle Ages, there are "apprentices" (junior managers or new hires), "journeymen" (mid-level managers or experienced professionals), and "master craftsmen" (senior partners or upper management). Some call these levels the "grinders," "minders," and "finders" of a firm, respectively.

Most professional services firms use a leveraging system to maximize profitability. For instance, junior employees usually earn a relatively low salary. They accept lower pay because they want to gain experience, and have the opportunity to work closely with senior partners ("finders") to acquire their valuable knowledge.