  The great diversity of the thousands of planets known to date is proof of the
multitude of ways in which formation and evolution processes can shape the life
of planetary systems. Multiple formation and evolution paths, however, can
result in the same planetary architecture. Because of this, unveiling the
individual histories of planetary systems and their planets can prove a
challenging task. The chemical composition of planets provides us with a
guiding light for navigate this challenge, but to understand the information it
carries we need to properly link it to the chemical composition and
characteristics of the environments in which the planets formed. To achieve
this goal it is necessary to combine the information and perspectives provided
by a growing number of different fields of study, spanning the whole lifecycle
of stars and their planetary systems. The aim of this chapter is to provide the
unifying perspective needed to understand and connect such diverse information,
and illustrate the process through which we can decode the message contained
into the composition of planetary bodies.
