The three main American branches of Judaism are Orthodox, Reformed, and Conservative. Orthodox Jews are by the book; they follow the Torah directly as it reads.
The Reformed branch is a group of Jews adjusting with the changes in the world. They are considered the liberal branch of Judaism. Conservative Jews are considered middle ground between the two other main American branches of Judaism.
There is another branch of Judaism: Zionism. Orthodox Jews have opposed this branch for a long time. These are the most common branches of Judaism in America. Below are links to pages on this topic.