Frequently PHP programmers get confused of the use of i month, -1 month, next month in strtotime() function. and hence it leaves some impression to programmer that this function is not that reliable.Let's take one example of strtotime call with -1 month and see why it leaves this impression.date("Y-m-d",strtotime("-1 month"))  // Assume today is 2018-07-31What's the output of above call? The answer is 2018-07-01. Why not 2018-06-30? So people get confused. It appears that this is wrong at first glance, but if think again, this output is reasonable.Below is how the logic worksIt first...