ISO 9000, in simple terms, requires an organisation to document its policies and procedures such that an external firm of assessors can inspect whether it does what it says it does.
This is why you often hear people saying that ISO 9000 means ‘say what you do and do what you say’. It is a ‘control’ view of the world, it is ‘quality assurance’, not quality improvement. It was only in 1994 revision that the Standard began to place any emphasis on improvement. No doubt this was in response to the obvious disasters which were occurring in British industry.
To note that the Standard now includes the requirement to ‘improve’ does not, however, mean that its followers necessarily will. Much of the thinking in the Standard shows a failure to understand how to improve performance with quality methods and, moreover, it encourages a ‘command and control’ view of improvement.
For a summary of its clauses see: ISO 9000 requirements