Most people meet SOP in a message rather than in a manual: follow the SOP, that is not the SOP, check the SOP. The letters stand for standard operating procedure, but the more useful question is what the sentence implies, because there are only a few possibilities and they call for different responses. This page is about reading that message correctly, including the common case where the SOP being referred to does not actually exist in writing.
The literal meaning, and the test for it
A standard operating procedure is a written document describing how a specific job is done, owned by a named person and carrying a version. The test for whether one exists is simple: ask where it is. If the answer is a link, it exists. If the answer is a description of the process, what exists is a custom that somebody is calling an SOP.
What the message usually implies
Follow the SOP normally means there is an agreed way and you are not using it. That is worth checking rather than accepting, because a surprising share of the time the document is older than the system it describes. Doing it the documented way when the document is wrong is not compliance, it is a different mistake.
What to do when the SOP is wrong
Find the owner named on it and tell them, which is a thirty-second job when the register carries an owner and an unbounded one when it does not. A procedure with no name against it is the most common finding in a neglected register, and it is why the correction never happens: nobody knows who is allowed to make it.
What to do when there is no SOP at all
Write the short version and send it to whoever asked. Most useful procedures are a page. The worked example on this site is a register of 48 of them, which is what a small organisation carrying 12 processes at four procedures each ends up with, and almost none of them started as a project.
Questions people ask about what does sop mean
What does SOP stand for?
Standard operating procedure: a written document describing how one job is done, with an owner and a version.
How do I know whether an SOP exists?
Ask where it is. A link means it exists; a description of the process means somebody is calling a custom an SOP.
What if the SOP is out of date?
Tell the owner named on it. If no name is on it, that is the actual problem, and it is the most common one in a neglected register.