CRM stands for "Customer Relationship Management" and represents the set of tools and relationship strategy implemented by a company. This term is commonly used to describe or define the platform that a company uses to manage this relationship. There are plenty of platforms available and their most common features are organizing customers (B2C or B2B) databases with customisable information about them and delivering bespoke messaging (through email, SMS and social media, for instance).

Examples of this kind of platform are: Mailchimp, Hubspot, Active Campaign, Salesforce, Pipedrive and many others.

Implementing a CRM (Customer Relationship Management) platform is fundamental to keep customers engaged in an ecommerce business. It doesn't matter if this company sells to people (B2C) or companies (B2B), every business should have a relationship strategy and a unified database (with segmentations implemented to help clustering customers).Thus, a CRM will help to send specific messages to each group of customers, based in their individual interests, behaviors and preferences.

EICOM Institute also recommends that you take a look at this article from Investopedia to learn more.