Middle English, layperson's prayer book, from Anglo-French, from Medieval Latin primarium, from Late Latin, neuter of primarius primary
A primer is a first textbook for teaching of reading, such as an alphabet book or basal reader. The word also is used more broadly to refer to any book that presents the most basic elements of a subject.
The Latin Enschedé Abecedarium of the late 15th century, translated into English as the Salisbury Prymer, has been identified as the earliest example of a printed primer. It presented the alphabet and several Catholic prayers.
Other historical examples of primers for children include The New England Primer (1680s) and McGuffey Readers (1836) in the US, and Bala Potam (Lessons for Children, 1850 & 1851) by Arumuka Navalar in Sri Lanka.