In the introduction part there is a description of corrosion definition, occurence reasons, corrosion types and the ways it takes effect on products and on engineering constructions in general. Some basic types of corrosion are desribed with photographs of corrosion examples. Electrochemical corrosion is further described, its formula, effect and scheme. After that, there is an analysis of medium agressiveness, which are those mediums, review with list of behaviour of certain materials in different mediums. There is a detailed description of corrosion examinations which can be laboratory, field and exploatation examinations. Hereafter, there is a closer description of laboratory examinations, methods of planning and preparation, samples selection, procedure and examination results. There is a reference to some basic laboratory examination methods followed by detailed analysis of optical method. With this analysis, a visual method of examination is also presented because these two methods often go along and are frequently applied one with another. There is an elementary description, oxidation formulas and description of equipment which is being used in this method. Thereafter comes the description of surface preparation for metal samples. It is followed with analysis of few optical methods like metallography, mirror reflection examinations, measuring of oxide film and comparation method of samples and etalons. In the experimental part there is a further research of mettalography. In the end, there is a conclusion with own analysis and reccomendation.