This was a brief treatise on the subject of website quality control. What have we learned?
Quality management consists of quality planning, quality control, quality assurance, and quality improvement, and it comes with a number of methods to identify (control), fix (improvement), and avoid defects (planning, assurance).
Website quality control entails the means to determine (a) whether websites meet our own expectations and (b) to what degree our websites meet professional best practices.
Quality control is important because otherwise we would have no way of knowing whether what we do and produce is any good. Quality control is professional; quality control saves time and money and sometimes nerves.
Quality control entails and must include a great number of tests, covering security, accessibility, usability, performance, functionality, maintainability, semantics, validation, layout and design consistency, typography, (general) code quality, and coding standard compliance.
In practice, quality control requires training, depends on our mindsets, stands and falls with automation, and needs enforcement.
And, finally, there are a gazillion tools for quality control and assurance.
Quality management is important, and no website should go without a plan for quality control.