He founded the Sri Ramakrishna Math and Mission on the principle of Atmano Mokshartham Jagad-hitaya cha (for one's own salvation and for the welfare of the World).

Vivekanda advised his followers to be holy, unselfish and have shraddha (faith) in the almighty. He encouraged the practise of Brahmacharya (Celibacy). In one of the conversations with his childhood friend Sri Priya Nath Sinha he attributes his physical and mental strengths, eloquence to the practice of Brahmacharya. Vivekananda left a body of philosophical works (see Vivekananda's complete works) which Vedic scholar Frank Parlato has called, "the greatest comprehensive work in philosophy ever published." His books (compiled from lectures given around the world) on the four Yogas (Raja Yoga, Karma Yoga, Bhakti Yoga, Jnana Yoga) are very influential and still seen as fundamental texts for anyone interested in the Hindu practice of Yoga. His letters are of great literary and spiritual value. He was also a widely considered a very good singer and a poet[citation needed]. He had composed many songs including his favorite Kali the Mother. He used humor for his teachings and was also an excellent cook. His language is very free flowing. His own Bengali writings stand testimony to the fact that he believed that words - spoken or written should be for making things easier to understand rather than show off the speaker or writer's knowledge

He conducted several public and private lectures, disseminating Vedanta, Yoga and Hinduism in America, England and few other countries in Europe.

The Swami is regarded as one of India's foremost nation-builders. His teachings influenced the thinking of other national leaders and philosophers.

He has written many books on various fields of Yoga.Some of these are as:-

> Raja Yoga by Swami Vivekananda ISBN 0-911206-23-X
> Karma Yoga and Bhakti Yoga by Swami Vivekananda ISBN 0- 911206-22-1
>The Yoga Sutras of Patanjali: The Essential Yoga Texts for Spiritual Enlightenment by Swami Vievkananda

Source:- http://en.wikipedia.org/