Transparent Language Inc. is a language learning software company based in Nashua, New Hampshire. Since 1991, Transparent Language has been offering its products to individual consumers, and in the past decade has grown to provide services for educational institutions and government agencies, ranging from MIT to the Department of Defense. Transparent Language’s products are developed based on the declarative method of learning. The human brain has two memory systems: declarative and procedural. The declarative system is responsible for remembering facts (such as words, phrases, or dates) while the procedural system learns skills (such as riding a bike). Language learning depends on both of these systems, as vocabulary is learned declaratively, and the associated grammar rules are learned procedurally by recognizing implicit patterns in the vocabulary and phrases learned. Backed by this linguistic research, the company holds the position that vocabulary is more fundamental to language learning than grammar. Since declarative items are best learned through repeated exposure, Transparent Language programs track learning and employ an algorithm to repeat vocabulary at the appropriate intervals to ensure memorization, a practice known as spaced repetition. A vocabulary item must be repeated several times to be considered “learned”, and after a specific period of time, these “learned” items must be refreshed in order to be committed to the memory.