An altar is simply a place to put your tools and the focal point for ritual, worship, or magick. Altars come in many sizes and varieties of setup, depending on use, space, and location. Anything will do for an altar, like a shelf, top of a dresser, etc. If  you wish an outside alter, a permanent stone or a tree stump works fine. Your altar can hold your magickal tools, sculpture of the god/dess (if you use one), seasonal greens or flowers, stones, tarot cards, etc. For most people, things of non-magickal nature are not placed on it (like your mail, house keys, etc.). Altars are a sacred place of prayer, ritual, and offering. Creating an altar is one of the first ways you can begin to feel the Pagan 'you' manifest.  It is something which will grow with you; change as you change. And it is something you will learn to construct to enhance your spells and rituals .Learning to create symbolically powerful altars, will really make your magick  more meaningful. Your altar is a symbol. It comes to be a microcosm of your Universe, using art and nature to signify all that is important in terms of your spirituality. Many people already have altars without even knowing it. How many people have a corner of their dresser laden with stones, rocks, feathers, flower petals, pictures, etc.? Why do we collect the things we do?, and then put those collections in places of prominence. Most of us will find that in times of crisis, stress, or just during a time in which we feel the need to be quiet and reflective, this 'altar' can be a haven. A Wiitch's altar is also a haven. It is carefully thought out and put together like a piece of spiritual artwork. Altars can be permanent or temporary. Permanent alters are great for witches who have the space and don't worry about privace (or have enough 'private' space that no-one will see it). Temporary alters are used when no permanent alter is available and a Witch needs to cast a circle during magick or ritual. Temporary alters can also be as simple as how they arrainge the flowers on their coffee table, laying out Tarot cards during a reading, or setting out a statue on the dash of their vehicle. After all, it is not necessarily 'what' comprises an altar, but what meanings are attatched to each item you place there. Setting up an alter: You need a space! How much space depends on the alters contents and how much space you have in the first place. Alters tend to grow fast (as you grow) so plan ahead. Next you need the physical alter, usually of wood (oak is good), but use your own judgement. There are a few ways to actually organize the altar. Some people divide the altar into sections, one area for each of the elements, and areas for symbols of the God/dess. The basic setup is: left side for the Goddess, right side for the God, Northern side for Earth, Eastern side for Air, etc. Again, do what feels most right to you. An example of an alter setup: Your altar is a place to honor the God/dess within yourself. Use it as a place of strength and fulfillment, and don't be afraid to change it at any time. We grow and learn everyday, and if your altar mirrors your self, then so too should your altar grow and change daily. You might reorganize and redecorate at each Full Moon, or at each Holy Day, or maybe just when it needs dusting. Whatever you do, take good care of it, and treat it with love and kindness.