What is a Standard Operating Procedure (SOP)? The word ‘Standard Operating Procedure’ shortly known as SOP, probably originated in military or healthcare domains to instill best practices in performing a specific function. SOP is a written document with step-by-step instructions to guide the performer of a process or a function or an activity. The purpose of SOP is not to teach someone how to do a work or to impart a skill, but to imbibe best practices that ensures some sort of standardization in performing a work in a most optimal way.