Theoretical High Energy Physics

Introductions to String Theory

A very good non-technical introduction is Beyond String Theory by Jan Troost.
For Dutch speaking readers, there is an interview with Alexander Sevrin in Knack, a leading Belgian weekly, by Dirk Draulants.
An introduction to string theory, black holes and cosmology, written by Ben Craps, appeared in the January 2015 issue of the monthly magazine “Heelal” (in Dutch).
In addition, Alexander Sevrin wrote a text (which appeared in the proceedings of the 2002 Rencontres de Moriond) Strings, Gravity and Particle Physics explaining the main principles and highlighting the major results of string theory. It is somewhat more technical than the previous links and aims at physicists in general.