Although analysts cannot agree on a definition of terrorism, they do generally agree on which episodes fit the description, and the very useful Encyclopedia of World Terrorism brings together in a readable and well-organized format information on much of the terrorism that has occurred in history, and especially in the twentieth century. Its 75 contributors and nearly 200 entries cover such varied topics as terror in the Roman Empire ("When [the Romans] make a desolation, they call it peace"), the morality of the Dresden bombings of 1945, and terrorist fundraising techniques.
Paying homage to the Middle East's particular reliance on this brutal form of political violence, roughly half the work deals with that region in the modern era. The entries tend to be reliable though without distinction; many authors lack a research knowledge of their appointed subjects, but instead rely on secondary sources (this applies, in particular to Neil Partrick and Andrew Rathmell, who together wrote nearly all entries about the recent Middle East). Some editorial decisions are open to question -- why entries devoted to Libyan, Iraqi, and Iranian state sponsorship of terrorism but not Syrian?
Of note is the fact that Indian customs agents in January 1997 impounded the thirty sets of this Encyclopedia the publisher had sent to India, due to the perceived "harsh treatment" of Sikh extremism and the people of Kashmir. Not only is the censorship of sober reference books a bizarre and pathetic response by the Government of India, but on reading the offending section (pp. 478-81), this reviewer cannot even figure out what triggered such a response.