The Abdus Salam Memorial Meeting was held from the 19th to the 22nd of November, 1997 on the first anniversary of the death of Prof Abdus Salam, Nobel laureate and Founder-Director of the International Centre for Theoretical Physics. It was an opportunity for many of his colleagues and students to pay homage to him. This invaluable volume, comprising the papers presented at the meeting, reflects the long-lasting passion of Prof Salam for the theory of the fundamental forces. Most of the contributions are concerned with recent developments in the theory of superstrings, including duality, D-branes and related topics.