Master's Level Work
Broadly speaking, the majority of post-bachelor degrees can be classified as master's level or doctoral level. Master's degrees (e.g., Master of Science (MS), Master of Arts (MA), Educational Specialist (Ed.S.), Master of Business Administration (MBA), Master of Fine Arts (MFA), etc.) generally involve two or three years of study. Those with master's degrees may teach at the community college level.
Why Graduate School?
Good reasons to continue your education beyond the bachelor's level include a desire to gain greater expertise in a particular topic (e.g., applied behavior analysis), explore a new area of interest (e.g., statistics), and/or prepare for a particular occupation. It is probably not a good idea to continue your education because you can't think of anything else to do or you think it would be impressive to have additional initials after your name. Graduate school involves significant emotional, intellectual, and financial investment; it should not be entered into lightly.