I Am Going To Yosemite National Park, And Would Like To Climb Half Dome. How Do I Go About It?

One of the premier hikes in North America is that to the top of Half Dome, towering above Yosemite Valley to an elevation of 8,842 feet.
Half Dome is made up from a type of granite -- plutonic rock-- and its missing half is presumed to have fallen off when the ice age glaciers passed through the valley
The hike is approximately 17 miles round trip, and can take anywhere from 10 to 12 hours. The elevation gained is 4,800 feet, from the valley floor (almost one mile).
There are two ways start the hike:
-- Happy Isles at the Vernal Fall trailhead. This heads to the Mist Trail then to Vernal and  Nevada falls.
--  Glacier Point via the Panorama Trial. This will take you to Nevada Falls to meet the trailhead to Half Dome. You'll need to be dropped off at Glacier Point (usually via a shuttle bus from the valley floor; buy tickets at any tour desk) then hike out to Vernal Fall to Happy Isles.
On the way down, you can either go the Mist Trail at Nevada Fall or the John Muir Trail (a horse trail). The latter is more gentle, yet can be almost as severe on the knees. Take a walking stick for the rocky trail down.
Start your hike as early as possible, preferably at the break of dawn. The shuttle buses to the Glacier Point trailhead start running at 7 a.m.
Take lots of water,  one-half to one gallon. Never hike Half Dome in a thunderstorm, as lightning may strike at any time. Near the top, you will be steadying yourself with a cable on a face that at some points is at a 45-degree angle.
It is a good idea to spend the night before the hike in Yosemite to become acclimated to the higher altitude if you are coming from lower than 4,000 feet.