The House of Representatives was originally set up to represent the will of the people of the United States. Unlike the Senate, it's members were always elected directly by the people, reflecting their will and needs. It was furthur crafted to this purpose by forcing its members to be re-elected every two years which makes them much more responsive to change.
In modern times, the number of representatives has been fixed at 435. To figure out which state get the most representatives the country must be divided up proportionally into "districts". Small states like Wyoming only recieve one representative while large states like California recieve many because of the size of its population.
Members of the House sit in committees where they debate and refine legislation before it is passed on. The House is also where the impeachment process for the president begins with a majority vote.