Hello everyone... Have a nice day... I'm wondering if anyone interested in theory of evolution, how it's happen, i can't understand...

If you're copying a book, you're going to make some mistakes. So does nature when copying DNA. When it does that quadrillions of times, one of those mistakes is bound to be an improvement. That organism is then more likely to survive and procreate, causing that DNA to spread more than that of the rest of the species.