Standard operating procedure (SOP)
SOPA standard operating procedure is a controlled written document that specifies exactly how a recurring task is to be performed, by whom and with what records.
In manufacturing and laboratory settings, procedures of this kind cover everything from cleaning equipment and weighing ingredients to sampling a batch and calibrating an instrument. Each is version-controlled, approved by the quality function, and used to train staff, so that the same task is done the same way regardless of who does it. Deviations are documented and investigated.
A customer never sees the procedures themselves, but their effects show in consistency between batches and in the reliability of test results. A laboratory accredited to ISO/IEC 17025 must have documented procedures for every method it reports, which is part of why accreditation carries weight. When a company says it follows good manufacturing practice, written procedures are the backbone of that claim. Their absence is one of the most common findings in regulatory inspections.