Infinity is an easy concept to come up with.One only has to look at the sky to imagine that space may go on forever. One may imagine a process or sequence of events carrying on forever. It is also natural to think whether your own world goes on forever, or if there is an edge of the world. Also, some optical illusions may make one believe that something was infinite. Last, but not least, religion has been linked to the concept of infinity from ancient times. God-like figures and Deities have frequently been attributed with infinite power, knowledge and existence.

• Potential or mathematical infinity: a process which has the potential of being infinite. For example, counting the natural numbers 1, 2, 3, 4, 5, ... is a potentially infinite task.
• Actual or physical infinity: an infinity which exists in nature. This category includes the infinitely large and the infinitely small. Examples of physical infinities would include the Universe (if it is infinite in space) or Time (if it is infinite).
• "Absolute" infinity: God.

About the symbol: The symbol of infinity was used by the romans to express a "large" number, and in many cases this large number was 1,000, which was "large" indeed at the time. John Wallis (1616-1703) was the first mathematician to use the symbol to denote an infinite quantity.

Click here for a biography of John Wallis.