The aura phase is a possible second phase of the migraine. Some people mistakenly believe that aura is a necessary symptom to be diagnosed with migraine; this is incorrect. In what is modernly known as a “common” migraine, a sufferer does not have an aura phase. When there is an aura, it typically follows the prodrome phase and precedes the "headache" phase, though it may overlap with these. The aura phase of a migraine may also be known as the "excitement" phase.
Unfortunately, experiencing an aura as part of a migraine is significant to a migraineur, as it can indicate an increased risk of stroke. Specifically, women who experience migraine with aura may be at a higher risk of heart disease and stroke. Women who have migraine with aura and are on a newer form of birth control may also be at a higher risk for blood clots.
Types of Aura
Another common misconception is that auras must always be visual. This is the most common form of an aura, but auras may also be auditory or any other type of neurologic symptom. Other types of aura include numbness or tingling in the face, arms, or legs, weakness along one side of the body, or difficulty with language.
A visual aura can also have a variety of forms. Visual aura manifestations include dots in the field of vision, zigzags, or shimmering crescent that gets larger until it temporary blinds the migraineur. Visual auras typically last under an hour; anything longer is considered a “prolonged aura.” 
- Tepper, Stewart J., M.D. Understanding Migraine and Other Headaches. UP of Mississippi, 2004, p. 7
- Gever, John. “Migraine with Aura Carries High Stroke Risk.” MedPage Today. http://www.medpagetoday.com/MeetingCoverage/IHC/40188. July 1, 2013.
- Glynn, Sarah. "Migraine With Aura Linked To Heart Disease in Women." Medical News Today. January 16, 2013. http://www.medicalnewstoday.com/articles/255013.php July 30, 2016.