"Śabda" (Sanskrit: शब्द, Word), in "Nyayasutras", means relying on word, testimony of a reliable source. "Sabda-pramana" has been an accepted and reliable method to knowledge by all orthodox schools of Hinduism including Nyaya, asserting that a human being needs to know numerous facts, and with the limited time and energy available, he can learn only a fraction of those facts and truths directly. He must rely on others, his parents, family, friends, teachers, ancestors and kindred members of society to rapidly acquire and share knowledge and thereby enrich each other's lives. This means of gaining correct knowledge is either spoken or written, but it is through "Sabda" (words). In addition to words, state the Nyayasutras, "Shabda" as a means of true knowledge depends on an agreed convention on what words mean, the structure of sentences, establishing context and their import. The source must be reliable and comprehensible, and the receiver of knowledge must be able to understand the knowledge therefrom.