The national Competency-Based Education Network, of which Texas A&M University - Commerce is a member, has developed a comprehensive and effective definition of CBE:

Competency-based education combines an intentional and transparent approach to curricular design with an academic model in which the time it takes to demonstrate competencies varies and the expectations about learning are held constant.  Students acquire and demonstrate their knowledge and skills by engaging in learning exercises, activities and experiences that align with clearly defined programmatic outcomes. Students receive proactive guidance and support from faculty and staff.  Learners earn credentials by demonstrating mastery through multiple forms of assessment, often at a personalized pace. 

The network also created a video that gives a clear overview of the basics and benefits of CBE: 

Although competency-based education can vary depending on the context, high quality programs include three components: clearly defined competencies, broad and deep curricula to support learning and instruction, and rigorous, carefully designed assessments. CBE meets the student where she is and takes her to where she wants/needs to be.