This document introduces various types of corrosion and degradation that can occur in plant equipment. It describes 8 basic types of corrosion: 1) chemical corrosion, 2) galvanic corrosion, 3) electrolytic corrosion, 4) crevice corrosion, 5) stress corrosion, 6) intergranular corrosion, 7) erosion corrosion. For each type of corrosion, it provides a brief definition and examples to illustrate how it occurs. The document emphasizes that corrosion is a major factor in the degradation of plant equipment and requires consideration during inspections.