n these lecture notes, an introduction to superstring theory is presented. Classical strings, covariant and light-cone quantization, supersymmetric strings, anomaly cancelation, compactification, T-du . . . . .

In this lecture notes we explain and discuss some ideas concerning noncommutative geometry in general, as well as noncommutative field theories and string field theories. We consider noncommutative qu . . . . .

The first part is an introduction to conformal field theory and string perturbation theory. The second part deals with the search for a deeper answer to the question posed in the title. Contents: 1. . . . . .

Notes of an introductory string theory course

This is the written version of a set of introductory lectures on string theory.

Contents: Strings in QCD; The classical string; Open and Closed strings; Quantization; Lorentz invariance; Interactions and vertex operators; BRST quantization; The Polyakov path integral. Interactio . . . . .

We give a pedagogical introduction to string theory, D-branes and p-brane solutions.

Contents: Elementary particle physics; String solutions and states; Strings in perturbation theory; Superstring theories; Dualities; M-theory and Branes; Selected topics of string theory.

Solutions to low energy string theory describing black holes and black strings are reviewed. Many of these solutions can be obtained by applying simple solution generating transformations to the Schwa . . . . .

These four lectures, addressed to an audience of graduate students in experimental high energy physics, survey some of the basic concepts in string theory. The purpose is to convey a general sense o . . . . .

We give an elementary introduction to classical and quantum bosonic string theory.

The 1988 book, now free, with corrections and bookmarks (for pdf). 247 pages.

Introductory Notes in Bosonic String Theory and its Canonical Quantization 39 pages.

In these notes we provide a pedagogical introduction to the subject of tachyon condensation in Witten's cubic bosonic open string field theory. 103 pages.