Urticaria and angioedema will affect 15-20% of the general population during their lifetime, and this remains one of the most vexing conditions to evaluate and treat. This review of the literature is to give the reader a global insight into the spectrum of urticaria and angioedema, focusing on differential diagnosis and pathogenic mechanisms. It will define the role of the mast cell, exploring a possible autoimmune basis for urticaria. Last, the different potential treatments will be discussed. Urticaria and angioedema are frustrating problems for both physicians and their patients; however, the problem may best be approached by considering urticaria as a general affection rather than a specific cutaneous disease. The physical examination and medical history remain the two most important pieces of information.