Piwik is an open-source web analytics platform developed by an international team of programmers as an alternative to Google Analytics. It is free to use and install, has a simple interface, and allows users to host the data wherever they choose. Some key advantages of Piwik include full access to log data, real-time reporting, extensive customization options, and keeping data independent and under the user's control. Initial installation of Piwik is relatively easy and quick, taking around 10-20 minutes to set up.