"Hanging" in traditional butchery refers to the practice of chilling or aging meat (suspended on hooks, hence the term "hanging") and game under closely controlled conditions until it reaches the peak of flavour and tenderness, before it is cut up for sale or consumption. The exact duration of this process differs from butcher to butcher but generally speaking, 10 days is more or less considered  the norm.

Connoisseurs will insist on a minimum hanging period of 2 weeks but will not balk at meat that has been hung for anything up to 6 weeks (and rumour has it, even 2 months *gasp*) after slaughter.

In reality though, this step has more or less been discarded in the practice of modern day butchery apparently in the interests of food safety or, perhaps, quicker and heftier profits. Just a thought... just a thought.

Hanging meat encourages the breakdown of muscle fibres through the action of naturally occuring enzymes, which tenderizes it and is also said to contribute to an improved flavour. The downside of hanging (for suppliers and retailers, not consumers) is that it causes the meat to lose moisture which in turn means weight loss and a compromised profit, for you know who. Hmm....

It's all good for steak and roast lovers though as all that evaporation means drier, less "weepy" meat that caramelises and crusts more willingly and quickly as well as a concentration of meat flavour. There is however, the ever present spectre or bogeyman perhaps, known as "spoilage" which suppliers and retailers insist is the only reason they've long jumped off the meat hanging bandwagon. It's all well and good, until you realise that there are supermarkets offering "dry aged" (a prettier name for hanging) meat that comes with an even princelier pricetag than usual.

In any case, I'm no expert on the subject, as the only remotely "aged" meat I can attest to is the tenderloin I personally tended to (see Roast Beef Tenderloin with Pumpkin Ravioli). For an authoritative account, dive into Hugh Fearnley-Whittingstall's "River Cottage Meat Book". I'm still learning, and, getting more sucked in everyday.