[question] can anyone explain to me moto GP tyres

I started following moto gp from this season. I haven't understood how the tyres actually affect the race and the different types of tyres. Explain please?

I started following moto gp from this season. I haven't understood how the tyres actually affect the race and the different types of tyres. Explain please? http://ifttt.com/images/no_image_card.png