People who left high school without graduating often find that employers and post-secondary institutions will not accept them without showing some form of academic competency. Since adults often cannot or will not return to high school, receiving the GED allows them to demonstrate that they possess a skill level comparable to that of an average high school graduate.
Approximately 95% of colleges will accept GED graduates, though they will typically require them to take the SATs and/or ACT. Some admissions boards request extra letters of recommendation in addition to the standard number already required of applicants when reviewing GED applicants. (Home schooled students who receive the GED are the main exception to this rule, since many home schooled students cannot receive traditional diplomas and need to finish their high school careers with the GED.) If a 4-year college will not accept a GED graduate, they can attend any community college in the United States, after which they can transfer to almost any 4-year school.
The main problem GED recipients encounter when trying to transfer from community colleges to 4-year schools is the lack of SAT and/or ACT scores, which GED recipients typically do not have. Due to this and other factors, most colleges do not require transfer students to submit such scores when applying beyond a certain point in their college careers, typically after one year or earning approximately 30 college-level credits. Many colleges, especially public institutions, also offer scholarships and other forms of financial aid specifically for GED recipients in order to help them finance their education.