The Cambridge encyclopedia of language - David Crystal

This new, thoroughly revised edition of the acclaimed Cambridge Encyclopedia of Language incorporates the major developments in language study which have taken place since the mid 1990s. Two main new areas have been added: the rise of electronic communication in all its current forms from email to texting, and the crisis affecting the world's languages, of which half are thought to be so seriously endangered that they will die out this century.
All language statistics have been updated, and additional information provided about their linguistic affiliation
All topics involving technology have been revised to take account of recent developments, notably in phonetics, language disability, and computing
Maps have been revised to include new countries or country names
Special attention has been paid to fast-moving areas such as language teaching and learning
The text design has been completely updated with many new illustrations throughout