A spirit animal is a guide that takes animal form. People often see their spirit animal in visions or dreams, but they can also appear in physical form as a natural animal. Some people even have mythical spirit animals, such as dragons, which of course cannot appear in their physical form. A spirit animal's power comes from its wild nature, so domesticated animals are rarely spirit guides.
You do not have one specific spirit animal. By which I mean, if your spirit animal is the deer, there is not one specific deer that is your spirit animal. Rather, it is the entire species that represents your spiritual guide. Related animals may also bear messages. If your spirit animal is a raven, for instance, crow sightings may also be significant for you.
So what does a sighting of you spirit animal mean? Often, people turn to their spirit animals for guidance when they are facing a decision about a relationship, a career, or seeking the purpose for their life. Your spirit animal can also appear to you when are you hurt and help you heal, either physically or spiritually.