Ultralight backpacking

Ultralight backpacking is a style of backpacking that emphasizes carrying the lightest and simplest gear safely possible for a given trip.Base pack weight (the weight of a backpack plus the gear inside & outside it, excluding consumables such as food, water, and fuel, which vary depending on the duration and style of trip) is reduced as much as safely possible, though reduction of the weight of consumables is also applied.

Light and ultralight are generally defined as base pack weights below 20 pounds (9.1 kg) and 10 pounds (4.5 kg) respectively in the US; elsewhere the definitions are commonly given as lightweight being under 10 kg, and ultralight under 5 kg. For comparison, traditional backpacking practices often results in base pack weights above 30 pounds (14 kg), and sometimes up to 60 pounds (27 kg).

Ultralight backpacking was popularized by rock climber Ray Jardine, whose 1992 book PCT Hiker's Handbook, later retitled as Beyond Backpacking in 1999, laid the foundations for many techniques that ultralight backpackers use today. Jardine claimed his first Pacific Crest Trail thru-hike was with a base pack weight of 25 pounds (11 kg), and by his third PCT thru-hike it was below 9 pounds (4.1 kg).

An early pioneer was Grandma Gatewood, who thru-hiked the Appalachian Trail in 1955 with only a duffel bag containing an army blanket, a plastic sheet, an umbrella, and other very simple gear much lighter than the heavy equipment common among thru-hikers in those days.

By carrying lighter and more multi-purpose equipment, ultralight backpackers aim to cover longer distances per day with less wear and tear on the body. This is particularly useful when through-hiking a long-distance trail. Many adherents suggest the following steps (in order of weight and least cost):

All these efforts can result in base backpacking weight that is under six pounds (3 kg). Although focusing on the pack's weight is common, the philosophy of ultralight travel applies to the person (e.g. trim vs. obese) and everything carried (e.g. skin-out weight).

...
Wikipedia