The Liberty Bell's inscription is from the Bible (King James version): "Proclaim Liberty Throughout All the Land Unto All the Inhabitants thereof." This verse refers to the "Jubilee", or the instructions to the Israelites to return property and free slaves every 50 years.
The State House bell, now known as the Liberty Bell, rang in the tower of the Pennsylvania State House. Today, we call that building Independence Hall.
No one recorded when or why the Liberty Bell first cracked, but the most likely explanation is that a narrow split developed in the early 1840's after nearly 90 years of hard use. No one living today has heard the bell ring freely with its clapper, but computer modeling provides some clues into the sound of the Liberty Bell.