Old Yankee's Bell
ndependence Hall, once known as the Old State House, was the home of the bell for many years since 1753. The bell was referred to as the "Independence Bell", or the "Old Yankee's Bell" until 1837 when it was named the "Liberty Bell", in part due to the adoption by the American Anti Slavery Society as a symbol of the Abolitionist Movement.
The Liberty Bell has been rung for many historical occasions, most noted on July 8th, 1776, to summons the citizens to hear the first reading of the Declaration of Independence.  Many other ringings include: The opening of the First Continental Congress on 1774, and after the battle of Lexington and Concord in 1775.

The Inscription
The source of the inscription for the bell is Leviticus 25:10.  It was also intended to mark the 50th Anniversary of William Penn's "Charter Of Privileges" in 1701.

Leviticus 25:10 
"And ye shall hallow the fiftieth year, and proclaim liberty throughout all the land unto all the inhabitants thereof: it shall be a jubile unto you; and ye shall return every man unto his possession, and ye shall return every man unto his family."
The Crack
It is reported that the crack was first noticed upon testing the bell in the town square prior to raising it to the bell tower in the Old State House.  The bell was re-cast by John Pass and John Stow of Philadelphia, while a replacement bell was ordered from Whitechapel. (The original makers of the bell)

The re-cast bell sound proved unsatisfactory, due to too much copper being added into the mix.  Pass and Stow re-cast the bell once again, correcting the mix of metals to improve the sound.  This third bell was then hung in the bell tower.
Upon receipt of the replacement bell by Whitechapel, it was determined that the new bell sounded no better than the old re-cast bell, so it remained.  The new bell was simply used at a time keeping bell.

It is not certain when the second crack developed, but repairs were made in 1846.  Then on February 22nd of the same year, the bell was rang to commemorate Washington's Birthday, when the repaired crack spread to the crown, rendering it unusable.  The bell was removed from the tower in 1852, where it was put on display in the Declaration Chamber of Independence Hall.  It now resides across the street, in Independence Center, where the bell can be viewed with Independence Hall in the background.

Details show the inscription on the "Liberty Bell" as well 
as the infamous crack