I am new to the series and I think that this has been asked many times - how the hell do the laws of time and space work in the series?

I have been watching the series lately, and I have arrived at the beginning of the 10th Doctor, but I am roughly familiar with the series, and yes, I do understand the joke of the timey-whimey thing.

But honestly, if the Doctor can travel through time and space and somehow, either the timeline changes, or it does not, and people tend to remember the Doctor as if he visited that point in time, and it was all like everything is normal.

Are there any rules on how the Doctor's appearances in certain time periods affect the trajectory of time?