The most commonly used lock today is the pin tumbler lock. A series of pins that are divided at certain points must be raised to these dividing points in relationship to the separation between the cylinder wall and the shell of the lock by a key cut for that particular series of pin divi- sions. Thus the cylinder can be turned, and the mechanism or lock is unlocked.
Lock picking means to open a lock by use of a flat piece of steel called a pick. Actually, the process requires two pieces of flat steel to open cylinder locks. It amuses me to watch spies and thieves on TV picking locks using only one tool. But it is for the better in a sense. If everyone learned how to pick locks by watching TV, we would all be at the mercy of anyone who wanted to steal from us, and the cylinder lock for the most part would be outdated.
The actual definition of lock picking should be: "The manipulation and opening of any restrictive mechanical or electronic device by usage of tools other than the implied instrument (key or code) used solely for that device." A little lengthy, but more accurate description. With cylinder locks, it requires a pick and a tension wrench.
By picking the lock, you simply replace the function of a key with a pick that raises the pins to their "break- ing point," and using a tension wrench one rotates the cylinder to operate the cam at the rear of the lock's cylinder to unlock the mechanism.
The tension wrench is used to apply tension to the cylinder of the lock to cause a slight binding action on the pins as well as to turn the cylinder after the pins have been aligned by the pick; this opens the lock. The slight binding action on the pins caused by the tension wrench allows one to hear and feel each pin as it "breaks" or reaches alignment with the separation of cylinder and shell. The vibration is felt in the knuckles and joints of the fingers, and the sound is similar to that of a cricket in an arm wrestling match-a subtle yet distinct click.
Usually you need very little tension with the wrench while picking the lock. In fact, it takes somewhat of a delicate, yet firm touch. This is the secret to picking locks successfully-a firm and yet gentle touch on the tension wrench. You should be able to feel the pins click into place with the right amount of tension; experience will be your true guide.
Half of your success will be based on your ability to use or improvise various objects to use as tools for your purpose. The other half will depend on practice. I once picked a pin tumbler lock using a borrowed roach clip and a hairpin. A dangerous fire was prevented and probably several lives were saved. The world is full of useful objects for the purpose, so never hesitate to experiment.