The person reading from the Torah must not touch the handwritten parchment; oils from one’s fingers could smudge or dirty the holy text. A pointer is used for this reason as well as to keep from possibly skipping lines, or reciting from memory. It is said that it is forbidden to pronounce in public even one word from the Torah unless it is read directly from the handwritten text.
Even though every synagogue has at least one Torah pointer, some people possess one of their own. When they go to services, and are called upon to read from the Torah, they can use their personal pointer.