The first four Nikaya-texts belonging to the Suttapitaka of the Pali Tipitaka which contains the sacred sayings of Gotama (Skt. Gautama) Buddha are of inextimable value since they provide important source-materials to study the religio-cultural history of the contemporary period. From the sociological point of view to they are of utmost significance, because they vividly present the daily life of the people of ancient India. Hence the importance of the Nikayas can neither be gainsaid nor exaggerated. In fact, this work contains an outline study of the four Nikayas, namely, Dighanikaya, Majjhimanikaya, Samyttanikaya, and Anguttaranikaya, which belong to the Theravada Pali Canon, on some select aspects in five chapters and three appendices treating of the age of the Nikayas, comparative study between the Sanskrit/Chinese Agamas and Pali Nikayas, their language, Buddha's discourses to the laity, teachings of Early Buddhism under the threefold divisions of Sila, Samadhi and Panna, discussions on administrative, social and economic condition of ancient India, Historical and geographical materials found in the Nikayas, mutual relation of the treatment of similes in the Suttas of those Nikayas. In the present work, on the whole, an attempt has been made to introduce the first four Nikayas-texts in their entirety.