This guidance presents an elementary overview of the validation and application of methods to examine visually recognisable substances in feed and food. Although quality parameters and criteria for visual inspection methods have been taken frequently from other major disciplines such as analytical chemistry and microbiology, it is necessary to aknowledge that visual examination is a completely different discipline, which needs different approaches. Basic principle is the the examination of undesirable substances or ingredients occuring as visible units of extremely larger size and dimensions than chemical molecules. As consequence, the statistical background and physical disctribution are principally different from molecules affecting the design and validation of visual examination methods. This guidance will present and discuss specific application of relevant quality parameters to visual detection methods including microscopy and a framework of dedicated sets of quality parameters for the domain of visual monitoring methods will be given, separate for quantitative, qualitative and estimation methods. Elements for the design of visual examination methods are presented and discussed in relation to quality parameters. Part 1 will provide the theoretical backgrgound and principles of quality and control for visual inspection. Part 2 consists of an overview of the relevant parameters and procedures for application, which can be used as template for a Standard Operational Procedure for validation in a quality management system.