Industrial maintenance usually refers to the repair and upkeep of the different types of equipment and machines used in an industrial setting. The basics can be broken down into the following five categories: general knowledge, mechanical knowledge, electrical knowledge, welding knowledge, and preventative maintenance. According to this wide variety of areas of expertise, maintenance technicians usually are multi-skilled individuals, proficient in many tasks. Industrial maintenance also involves a great degree of problem solving skill. Identifying the problem alongside the best and safest means of resolving the difficulty typically are integral parts of the maintenance process.