Learning that must be accomplished successfully before more advanced learning can be started. More specifically, a prerequisite is often a course that a student is required to take before taking another (algebra before calculus, for example). A prerequisite is also a skill that is felt necessary before a high-level skill can be learned, in this sense also called a precursor skill or learning readiness skill. For example, a young child must learn to distinguish between an apple and a pear before beginning to learn their names, so telling the two fruits apart is a prerequisite or precursor skill. Word-attack skills are regarded as prerequisites for effective, independent reading, and reading is itself a prerequisite for most other academic learning.