A CRM (Customer Relationship Management) app is a tool that allows you to organize contact info and manage relationships with current and prospective customers, clients, and other contacts. It's the modern version of a Rolodex, but with more features and capabilities. A good address book app like Google Contacts can list contacts, add detailed contact info, write notes, and find emails, but a CRM does much more, including tracking potential customers and clients as "leads," adding info as you work on convincing them to use your product or service, and turning those leads into "deals" once they've decided to buy. There are four main types of CRM software: Operational, Collaborative, Analytical, and Marketing CRMs. These types cater to different needs and industry-specific requirements. A CRM can help you make order out of the chaos of your interactions with people, letting you focus on customers instead of trying to find out what was said last. It can also automate tasks, streamline business processes, and provide analytics and reporting to improve customer relationship management.