Crampons have revolutionised mountaineering and ice climbing; Ice routes like Point Five Gully on Ben Nevis were once climbed siege-style over a number of days, using ladders of laboriously cut steps. Those same routes can now be climbed in just a few hours using modern crampons with front points.
There are now crampons suitable for every activity on snow and ice; from gnarly ice falls to peaceful winter hill walks.
It's essential that crampons are fitted only to stiffened mountaineering boots (referred to as B1, B2 or B3 following a ratings system devised by the mountaineer Brian Hall). Fitting a stiff crampon on to a flexible boot could lead to the crampon falling off mid-climb, with potentially disastrous consequences.
For ice climbing, an ideal set-up would be a pair of B3 rated mountain boots with C3 technical crampons. The more aggressive front points give extra bite. These styles can also often be adapted to a mono-point set up for even better penetration and precision on hard ice. Attachment is usually by a metal front bar and rear heel lever which will only work on a B3 boot.
When mountaineering – perhaps doing the easier Scottish winter gullies or alpine routes – a C2 crampon will be technical enough for the climbing while still being relatively low-profile. The attachment system will be a rear heel lever and front toe cage, strapped together on a B2 or B3 boot.
For snowy walking, such as winter Munro bagging or on the easiest routes on Mont Blanc, a C1 crampon will be ideal. These styles strap on and flex with B1 rated boots, though they can also be fitted to stiffer B2 or B3 boots. They have low-profile points which give excellent grip on snow but are also easy to walk in.