What is a consulting company? What the hell are they doing?

At present, there are many kinds of consulting companies, including enterprise consulting, real estate consulting, financial consulting, marriage consulting, psychological consulting and so on. So what exactly is a consulting company? The American Consulting Association has a definition: "Consulting refers to providing information and suggestions based on professional knowledge." The task of researchers and consultants in consulting companies is to find out the problems of customers and propose solutions according to their professional knowledge and experience. It can be said that the consulting industry is to provide "intellectual services" to customers. Simply put, it is to provide external brain IQ services to help customers solve problems. Take enterprise consulting as an example. Usually do business diagnosis, process optimization, human resource performance evaluation and so on.