Customer relationship management (CRM) is a way of tracking a company’s interactions with customers and clients. It involves using technology to organise and automate communication. CiviCRM is a free sofware internet-based approach to CRM, aimed specifically at NGOs, charities and other civic groups. In practice, it can be used by any organisation that would benefit from keeping track of their contacts. This is done with various tools that can help you with things like fundraising, event management, member management, mass e-mail marketing, peer-to-peer campaigns and case management.

Creating and running a membership scheme for a donation-based charity
Maintaining a series of mailing lists for different interest groups within a wide network of groups and individuals

A free tool for performing complex tasks, with a good community behind it
Sets out a framework of tasks suitable for internet-based organising

Can be difficult to set up and keep up-to-date, so you may need help