iTunes gift cards are specific to the country they were purchased in. Therefore, when redeeming a gift card, make sure to do so in the iTunes Store of the same country. It's not possible to redeem gift cards outside of the country of purchase.
<aside> ⛔ For example, a gift card purchased in the United States can't be redeemed in an iTunes Store in Switzerland.
</aside>
iTunes Gift Card (US)
iTunes Gift Card (HK)
iTunes Gift Card (AU)
iTunes Gift Card (UK)
iTunes Gift Card (ZA)
iTunes Gift Card (NL)
iTunes Gift Card (RU)
iTunes Gift Card (CA)
iTunes Gift Card (AT)
iTunes Gift Card (IE)
iTunes Gift Card (IT)
iTunes Gift Card (SG)
iTunes Gift Card (SE)
iTunes Gift Card (DK)
iTunes Gift Card (CH)
iTunes Gift Card (PL)
iTunes Gift Card (JP)
iTunes Gift Card (ES)
iTunes Gift Card (TR)
iTunes Gift Card (DE)
iTunes Gift Card (FR)
iTunes Gift Card (PT)
iTunes Gift Card (MX)
iTunes Gift Card (CN)
iTunes Gift Card (FI)
iTunes Gift Card (BE)
iTunes Gift Card (SA)
iTunes Gift Card (NO)
iTunes Gift Card (UAE)
iTunes Gift Card (NZ)
iTunes Gift Card (TW)