These days many people attend community colleges with plans to transfer to a four-year college or university to get a bachelor's degree. It's kind of like a stepping-stone. There are many reasons why people do this. One reason is that some community colleges have transfer agreements with private and state colleges and universities that guarantee admission. Even if a community college doesn't have that agreement of a guaranteed spot in a four-year college, it has articulation agreements with four-year schools. These agreements tell you exactly what classes a student in a community college needs to take in order to be able to transfer. These agreements make sure that students don't waste time taking classes that won't transfer. Most of these classes one needs to take before transferring are general education classes, like math and English.
Another reason why many students start their undergraduate degree at a community college is a financial one. A four-year college or university is much more expensive than a two-year college. This is especially true for immigrant students, who don't qualify for financial aid, loans or scholarships. Also community colleges tend to offer more evening classes so they can accommodate people who have to work while attending school. They are also a good option for older students with families, who need a more flexible schedule while taking care of children. Community colleges also tend to be commuter schools, meaning people don't have to live on campus in dorms. Attending a community college means you can still live at home with your parents, which can save the family a huge amount of money.
If a student didn't do well in high school, a community college would provide him or her with another opportunity to enter a four-year university. Community colleges offer many classes to help students develop their math and writing skills. When you attend a four-year college, you are expected to have those skills already. Community college will prepare students to successfully graduate from a four-year school.