Congress has the power to make new laws, change existing laws, raise and support armed forces, declare war, establish post offices, secure patents and copyrights, collect taxes, regulate commerce, oversee the national budget and regulate other aspects of national finances. It also has the power to investigate other branches of government, confirm presidential appointments, ratify treaties and impeach the president and other federal officials.
Although anyone can write a law, only Congressional members can introduce it as a piece of legislation. It then goes into a subcommittee, where it is accepted as is, amended or rejected. After debating it, if both houses of Congress approve the bill by vote, it is passed on to the president. If the president vetoes the bill, Congress has the power to override the veto by a two-thirds majority.
To create the budget for the federal government, Congress can not only levy taxes and tariffs but also borrow money. Its authority to appropriate money for specific purposes as well as its power to investigate accusations of wrongdoing by government officials provide checks on the other branches of government.
Besides its specific powers enumerated in the Constitution, Congress has implied powers granted by the Necessary and Proper Clause in Section 8 of Article I. This grants Congress the authority to create any laws necessary to execute the powers given to it by the other sections of Article I.