I have been using Tarot cards since I was 12 years old. At some point I was told that they were "of the Devil" and I put them away off and on for a couple of years, but they were never far from my mind. I finally brought them out permanently when I was around 20 years old.
The Tarot is a deck of 78 cards. 22 are Major Arcana, and the rest are the Minor Arcana. The Minor Arcana are divided into 4 suits - usually wands, cups, swords, and pentacles though they may have other names such as rods or staffs, coins, etc. depending on the deck and its author's views. There are also court cards in each suit consisting of a page, knight, queen, and king. Again, these cards may be renamed such as prince, princess, daughter, son, priestess, shaman, etc. depending on the author's view.
Many of the cards are based on what many people refer to as the Rider-Waite Tarot. This deck is now more appropriately referred to as the Waite-Smith deck as Smith was the woman who did the illustrations. Some people refer to this deck as the Rider-Waite-Smith deck. Whatever you want to call it, it is the first common deck to display pictures for the pip cards, and many current decks are based on these images. (Yes, the Waite-Smith deck is based on the much earlier Tarot de Marseille deck, but this is a beginner's blog, so we won't get into that here. Yet.)
The pip cards are the Ace-10 cards in each suit. In the past they were represented merely by the number of objects for that suit. For example, the 5 of swords displayed 5 swords on the card. The Waite-Smith deck includes images with people and various colors for all of the cards. This practice to include people in various situations has become so common that it is now considered the norm. If a deck is purchased that features only the number of the objects on the pip cards, there is much backlash and lamenting about this in reviews of the deck.
How do we use Tarot cards? Tarot cards help to clarify our conscious choices as well as to look at our subconscious issues. They can help us understand why we have made our choices and can help us decide whether or not we need to change the direction of our lives. If we do decide to make changes, the cards give us clues as to what the best new choices may be. Sometimes it is easier to have others read the cards for us because we are too close to our own issues. This will also give us different perspectives on the meanings of the cards, and may help us view our question from a new angle.
I have given readings both in person and over the internet and have several favorite Tarot decks that I use. The Gilded Tarot by Ciro Marchetti has served me well the last few years. So well, in fact, that I own two decks! The colors are bold and the characters literally spring to life off of the cards. There are a variety of minor characters and animals on the cards as well, to help trigger the subconscious. I recently bought Ciro Marchetti's Legacy of the Divine Tarot. Without the gold border, some of the images seem to float. At other times, the images may seem darker due to the black border. However, this interpretation can vary due to the subject matter at hand.
Another favorite deck of mine is Tarot of the Magical Forest by Lo Scarabeo. This whimsical deck features animals as the main characters. I bought it by chance and expected it to only serve as an "art" deck, but it has proven to be far more insightful than I first suspected.
Before going out to purchase your own deck of cards, take some time to browse these and others at http://www.aeclectic.net/tarot/cards/ . There are over 1,000 decks with examples and reviews at this site. I own over 50 decks now, some for the artwork and some to work on specific issues.
One caution: Oracle cards are different from Tarot cards. Tarot cards feature 78 cards with 22 Major Arcana cards. Oracle cards may feature any number of cards and are usually based on the creator's dreamwork, research, or own metaphysical experiences. I personally do not have good results with Oracle cards in general, especially when reading for others. They are often too-narrowly focused on a specific set of characters or situations. Many decks are 40 cards and feature animals, angels, or one-word answers. Instead of allowing the reader to explore subtle nuances and a variety of possible answers or directions, Oracle cards often seem to attempt to provide a short, pat answer. That being said, there are many people who have great experiences with Oracle cards. I am just not one of them.
Tarot cards are based on characters and stories that are stored in our collective conscious. Jung referred to them as "archetypes," and even Joseph Campbell had a few things to say about them (though I'm not sure how much experience he actually had with the cards). More people can generally relate to the Tarot cards because their stories are all of our stories.