What is the use of exits present in IBM Websphere MQ ? Could anyone quote some real time example where it will be used?

What is the use of exits present in IBM Websphere MQ ? Could anyone quote
some real time example where it will be used?

I am currently working with IBM MQ 7.0 and we have never used exits and I
need to know in which scenario it can be best used. Needed some real time
example where it will be used ?