Ah, blisters... we've all had them, whether it was part-way through the school sponsored walk or because you were a bit clumsy that time you tried to take your apple crumble out of the oven. Maybe even when you had chicken pox as a child, or perhaps you over-indulged out on the ultraviolet rays at the beach. Blisters. Bloody things... sometimes literally.
Any one of those situations up there can cause a blister, and plenty of other situations beside. There's friction, where all you need for a blister to form is some sort of injury to the skin which creates a split between the upper layer of skin (the epidermis) and those beneath. Short periods of intense rubbing, or gentle rubbing over a longer period will do, and it's especially easy if the skin is moist and soft. It's easy to see why blisters are common on the hands and feet, and often occur when walking or running. And there you go: the damage is done, and blood serum seeps into the space between the two layers, pushing out the surface of the skin. Perhaps, if you've been particularly rough, a small blood vessel near the damaged layer will rupture, and instead of clear, transparent serum you'll get a small bubble of blood, often known as a blood blister.
Contact dermatitis is the blistering of skin from some form of irritant, perhaps detergent, solvent or some other corrosive chemical. The formation is the same - damaged skin leads to a swelling of serum. Similarly, the damage caused by a sudden application of heat may lead to a blister, or some form of disease - I mentioned chicken pox earlier, and you can add herpes, impetigo and a number of other skin disorders to that list. Of course, if you are blistering unexpectedly, what are you doing sitting round searching for 'blistered penis' in Google? I agree, the internet is a great source of information, but it's no substitute for medical help.
Many people dig out the needles as soon as a blister appears, occasionally passing it through a flame before using it to break open the beautifully sealed natural barrier of skin which is currently protecting the damaged layer beneath. Don't do it - an unbroken blister will heal perfectly on its own in the majority of cases, and will break open naturally once the skin beneath has healed, allowing the dead layer of epidermis to flake off. It's hardly glamorous, I realise, but at least you won't end up with an infected blister and a course of antibiotics.
Soft sweaty feet, rough socks and a pair of new shoes... ack - hang on, no! Scrub that clearly bad advice and instead get yourself a pair of well-fitting shoes, clean and dry socks, and perhaps some talcum powder to keep your feet dry and lubricated. When breaking in new shoes, don't be afraid to put a sticking plaster or some sort of spongy padding over areas that feel uncomfortable.
Wear gloves when gardening, and perhaps some more talcum powder. Shovel or pickaxe handles look beautifully smooth, but their constant rubbing is slowly working away to produce blisters on those soft, sensitive areas of your hands.
Going out on a hot summer's day? Don't forget that golden piece of advice... you're just as free to wear sunscreen as everyone else.
Oh, and oven gloves? They're what's for dinner...