This is an interesting topic, at my first job I've developed some tool to help our customer support, it's a topic which is quite interesting for me. On what da

This is an interesting topic, at my first job I've developed some tool to help our customer support, it's a topic which is quite interesting for me. On what data do you train your models? Do you train them individually for each customer with their own data, or do you take the data of all your customers and train "universal" model? Another question about the broader categories, are they defined by you? I guess you're doing some supervised learning. Is it possible for the customer to add own categories?