Oracle cards are a form of divination tool that's produced in a beautiful and accessible card format. As a divination system, oracle cards differ from tarot cards in that there's no set number of cards in a pack – they vary according to their own particular design and style.
There are a wide variety of different types of oracle cards available, from those focusing on angels and goddesses, to cards based on animal, crystal, shamanic or Celtic themes. When you're choosing which oracle cards to buy, use your intuition and opt for the pack you feel most drawn to. It may be the theme that you particularly resonate with and want to learn more about, or you may be drawn to the style of artwork used. Either approach is fine, especially since oracle cards are all about enhancing your intuition.