A reading of a bill is a debate on the bill held before the general body of a legislature, as opposed to before a committee or an other group. In the Westminster system, there are usually several readings of a bill among the stages it passes through before becoming law as an Act of Parliament. Some of these readings are usually formalities rather than substantive debates.
A first reading is when a bill is introduced to a legislature. Typically, in the United States, the title of the bill is read and immediately assigned to a committee. The bill is then considered by committee between the first and second readings. In the United States Senate and most British-influenced legislatures, the committee consideration occurs between second and third readings. In Israel, the committee consideration occurs between first and second readings and (for private member bills) between preliminary and first readings.
In Ireland, the first reading is referred to as "First Stage" and is leave to introduce a bill into a House of the Oireachtas. It may be taken in either house, but it does not need to be taken in both.
In New Zealand, once a bill passes first reading it is normally referred to a Select Committee. However, a Government can have a bill skip the select committee stage by a simple majority vote in Parliament.
A bill can be defeated on first reading if a member introduces it and no one seconds it.
A second reading is the stage of the legislative process where a draft of a bill is read a second time. In most Westminster systems, a vote is taken on the general outlines of the bill before being sent to committee.