This study will examine microbes (e.g., bacteria, fungi, viruses) that live on human skin and how microbes contribute to health and disease. It will analyze healthy human skin and how the these microorganisms might change in patients with atopic dermatitis (AD), a skin condition also known as eczema. Healthy volunteers, as well as patients with moderate to severe eczema (AD), between 2 and 40 years of age may be eligible for this study. We also wish to enroll children and adults aged 2-40 who have been diagnosed with inherited immune disorders known as HIES (hyperimmunoglobulin-E syndrome), WAS (Wiskott-Aldrich syndrome), or DOCK8 immunodeficiency because they frequently have skin problems similar to AD. Eligible participants undergo the following tests and procedures: * Medical family and medication history * Skin examination * Blood tests (research blood as well as serum IgE, and complete blood count) * Skin samples to analyze microbes. Samples are obtained by the following methods: swabbing the skin with a cotton swab; scraping (scratching) the skin gently with a blade to remove only the outermost skin layers; and, only in adults, biopsy (surgical removal) of a small skin sample less than 1/4-inch (5 mm) in diameter. * Nose swabs to analyze microbes. * Patients with eczema may have photographs of their skin taken to help monitor the skin rashes. Participants may be contacted periodically for follow-up studies. Patients with atopic dermatitis may have additional skin samples collected to examine changes in the skin bacteria over time and during all of the stages of eczema. In addition, patients who have a flare of their eczema are asked to undergo a skin sample collection as soon as possible.