This is a lesson that gives a short, hopefully easily digestible presentation of the difference between the simple past and the present perfect.
The simple past talks about actions in the past that are finished and happened at definable point in time.
I visited San Francisco back in 1997 when I was on my way to Korea.
The present perfect describes an action that began in the past, but its effect is still being felt. It often has the idea of 'up until now'.
I have lived here for many years.
Also, it can describe repeated past actions like how many times you have visited somewhere.
I have been to Korea many times, like around 5 times.