Within maintenance activities and industrial operations, human is subjected to different kind of stresses and situation that could result in mistakes and accidents. The human errors in maintenance and manufacturing are an unexplored latter such that a little focusis invested in this area. The report aims to widen up the understanding of the human error in maintenance and manufacturing area. Aviation and marine operations are the most sectors that are subjected to human errors according tothe literature. There aredifferent types of human error that have effect on quality and overall effectivity. Human reliability models are one method to quantify human errors and usually used for the identification of human errors and HEP calculation. The most common reliability measurement methods are HEART, THERP and SLIM which are used depending on application and industry. As a part of efforts to define differences between those reliability models, literature including different industries is used and itis found that expert judgement influences the success and accuracy of such methods. There are many causes for human errors depending on the application but, communication and procedures followed are the most contributing factors. There is always a probability of existence of human errors as the mistake done by workers are inevitable. Industry 4.0 can help in decreasing human errors through the introduction of operator 4.0 as well as other approaches like training and upgrading organizational standards.