Author: Ronald Brown Author's e-mail address: r.brown@bangor.ac.uk Author's web page: http://www.bangor.ac.uk/~mas010 Author's mailing address: Professor Emeritus R. Brown, Department of Mathematics, University of Wales, Bangor Dean St., Bangor, Gwynedd LL57 1UT, United Kingdom AMS classification number: 18D05,18D15,18G50,55P15,55U40,57M07 arXive submission number: math.AT/0407275 Abstract: We sketch the background to a book with the title `Nonabelian algebraic topology' being written under support of a Leverhulme Emeritus Fellowship (2002-2004) by the speaker and Rafael Sivera (Valencia). The aim is to give in one place a full account of work by R. Brown and P.J. Higgins and others since the 1970s which defined and applied crossed complexes and cubical higher homotopy groupoids to local-to-global problems and homotopy classification of maps. This yields a distinctive account of that part of algebraic topology which lies between homology theory and homotopy theory, in which the fundamental group and its actions plays an essential role, and which allows for nonabelian calculations in dimension 2. This is an extended account of a short presentation with this title given at the Minneapolis IMA Workshop on `$n$-categories: foundations and applications', June 7-18, 2004, organised by John Baez and Peter May.