A bicameral system is a style of government with two separate divisions within the legislative branch.
The US bicameral system consists of the House of Representatives and the Senate.
Most international governments use a unicameral system with a split between unicameral and bicameral about 60/40.
Each chamber of the legislature has different powers to provide a system of checks and balances.
The larger branch of the House of Representatives has less stringent membership requirements when it comes to age and duration of citizenship than the Senate.