The Legislative Branch is made of two parts: the Senate and the House of Representatives. Together, they form what is known as the United States Congress. As its name implies, the Legislative Branch is responsible for the creation of laws. Congress also has other powers, such as the ability to declare war and to decide on Presidential appointments.
There are 100 senators that serve in the Senate, each state having two. Since the 17th Amendment was ratified in 1913, senators have been chosen by popular vote in their state and serve a six year term. In order to be eligible to become a senator, one must be an American citizen, be over 30 years of age and reside in the state they represent. The head of the Senate is the Vice President of the United States, however he does not take part in votes, unless the vote has resulted in a tie. One responsibility of the Senate is to approve Presidential nominations to important positions, such as Supreme Court and federal court judges.
The House of Representatives has 435 members. The number of representatives from each state varies depending on the population of that state. Therefore, it is normal that a state which has a higher population, like California, will have a higher number of representatives than a less populated one such as Alaska. Representatives are elected for a two year term. To be eligible for election to the House of Representatives, one must be a U.S. Citizen, reside in the state they represent and be at least 25 years old. There are some special powers which are assigned exclusively to the House of Representatives, such as the ability to elect the new President should there be a tie in the electoral college.