What are the assumptions of linear regression Can anyone explain the assumptions of linear regressions?  

If possible with an example?

Is this really important to check these assumptions before proceeding?
Here are the links I have found: 

https://en.wikipedia.org/wiki/Linear_regression#Assumptions

https://www.statisticssolutions.com/assumptions-of-linear-regression/

http://r-statistics.co/Assumptions-of-Linear-Regression.html