Simplify the following text for a Grade 9 native English-speaking person.
Original: The term software engineering first appeared in the 1968 NATO Software Engineering Conference , and was meant to provoke thought regarding the perceived `` software crisis '' at the time . The IEEE Computer Society 's Software Engineering Body of Knowledge defines `` software engineering '' as the application of a systematic , disciplined , quantifiable approach to the development , operation , and maintenance of software , and the study of these approaches ; that is , the application of engineering to software .
Simplified: Software engineering can be very difficult work .