Petition descends from Latin petere, a verb with a surprisingly wide range: to seek, to aim at, to attack, to request. The common thread is directed motion toward something — whether hostile (attacking an enemy) or supplicant (requesting a favor). Latin petitio, the noun form, could mean an attack, a candidacy, or a legal claim, depending on context. English retained only the request meaning.
The Proto-Indo-European root *pet- meant to rush or to fly. This produced Latin penna (feather, from the earlier form petna) and through it English feather, pen, and pennant. It also generated compete (to seek together, that is, to rival), appetite (to seek toward, to desire), impetus (a rushing toward), repeat (to seek again), and perpetual (seeking through to the end). The family is held together by the concept of directed, energetic movement.
In medieval English law, petitions were the primary mechanism by which subjects communicated grievances to the crown. Parliamentary petitions shaped English constitutional development for centuries. The Petition of Right (1628) and the Bill of Rights (1689) both formalized the principle that petitioning the sovereign is a protected act, not a punishable one.
The American Constitution adopted this principle directly. The First Amendment protects the right of the people to petition the Government for a redress of grievances, placing it alongside speech, press, religion, and assembly as a foundational liberty. Historically, the right to petition predates free speech protections in English legal tradition.
Modern petitions have migrated online. Platforms like Change.org and parliamentary petition systems process millions of signatures annually. The legal and political weight of these digital petitions varies enormously by jurisdiction, but the core act — formally requesting that authority address a grievance — remains recognizably the same as when medieval subjects scratched their marks on parchment rolls bound for the king's council.