Its pure HELL and exceptionally itchy!
Seriously though, a quick search on google will generally tell you its a a general term for skin inflammation. Its an overused term in my opinion whereby anyone with some dry skin will complain about eczema (yeah, its a sore spot for me considering what I have gone through).
I love the picture Wikipedia has here: Wikipedia – Eczema, its a picture of someone with eczema on the hands.
I do enjoy the following explanation of cause on wikipedia:
The hygiene hypothesis postulates that the cause of asthma, eczema, and other allergic diseases is an unusually clean environment. It is supported by epidemiologic studies for asthma. The hypothesis states that exposure to bacteria and other immune system modulators is important during development, and missing out on this exposure increases risk for asthma and allergy.
While it has been suggested that eczema may sometimes be an allergic reaction to the excrement from house dust mites, with up to 5% of people showing antibodies to the mites, the overall role this plays awaits further corroboration. “
So, if I have this right….. they have no clue. It’s correlated to some other conditions such as asthma, allergies and has some genetic component.