A select committee is a committee made up of a small number of parliamentary members appointed to deal with particular areas or issues originating in the Westminster system of parliamentary democracy. Select committees exist in the British Parliament, as well as in other parliaments based on the Westminster model, such as those in Australia, Canada, Hong Kong and New Zealand.
It is a special subcommittee of a legislature or assembly governed under a committee system, like Robert's Rules of Order. They are often investigative in nature, collecting data or evidence for a law or problem, and will dissolve immediately after they report their findings to their superiors.
These are very common in government legislatures, and are used to solve special problems, hence their name.
United States
In the United States, notable select committees include the Select Committee on Presidential Campaign Activities (for investigating Nixon's role in Watergate) and the Select Committee on Benghazi.