Why did I have to pay customs tax for a skateboard I ordered from America? 1 answer below »

So a while ago I ordered 2 skateboard decks, 1 for me and 1 for my friend. The shipping cost a bomb and the delivery took over 3 weeks. And on top of that I got a letter saying that customs had intercepted my package and that I would have to pay £28 for it to be delivered! I was completely pissed off and now I never want to order anything from abroad again. Please could someone tell me why my package was intercepted and what I could do in future to prevent this from happening to me again.