Localized corrosion is best described as:

Localized corrosion is characterized by its occurrence at very specific, small areas on a material, rather than being widespread. This type of corrosion often leads to a greater concentration of damage in localized spots, potentially resulting in significant structural issues despite the overall appearance of the material appearing intact.

For instance, pitting is a common form of localized corrosion where small pits form in the surface due to chemical or electrochemical reactions. These localized areas can penetrate deeply into the material, causing significant problems, as the surrounding area may show little or no damage. The critical aspect of localized corrosion is its difficulty in detection until serious damage has occurred, which can be misleading because it may not be evident until the integrity of the structure is compromised. Thus, the nature of localized corrosion is primarily defined by its confined attack rather than a uniform or widespread deterioration.