Sonic Pi is an Integrated Development Environment (IDE) for writing music in Ruby. It allows users to interact with their computer as if they were using a synthesizer, and can be used to create complex electronic music compositions. The basic syntax of a loop in Sonic Pi involves naming the loop, calling in a synth or sample, and adjusting the timing with sleep. Users can add multiple loops to create a full sound, and also use effects such as distortion to modify the sound. Additionally, users can play notes using the `use_synth` method, and add audio samples to their composition. The IDE has a built-in documentation feature that allows users to experiment and learn from examples. With its user-friendly interface and powerful features, Sonic Pi is an ideal tool for musicians and music producers looking to create complex electronic music compositions.