More and more computers are being used for writing texts. With the development of Unicode, which supports more than 110,000 characters, it is currently possible to write in almost any language. However, most of these keys are not on your keyboard. GNOME, Unity, KDE and other X11-based desktop environments, fortunately, offer various mechanisms to enter characters from this vast range. One way is by using compose key sequences, of which over 4,000 exist. Even though compose key sequences are relatively easy to remember, it is still a challenge to find out which are available for the characters you regularly need when writing or programming on your computer. Multiple practical overviews of almost 2,800 compose key sequences are provided by this reference guide. Most of these sequences result in Unicode characters which are not available on your keyboard and related mainly, but not exclusively, to Western languages. This reference guide allows you in a unique way to quickly find compose key sequences you are looking for and discover a myriad of new characters to easily use in your texts.