The fourth Tate Triennial, curated by Nicolas Bourriaud, opens at Tate Britain in February 2009.

It will explore what 'modern' means now, in the globalised culture of the early 21st century. Bourriaud has come up with the new concept: 'Altermodern', and he uses this to describe art being made now that belongs to the global era and is a reaction against standardisation and commercialism.

This art is characterised by artists' cross-border, cross-cultural negotiations; a new real and virtual mobility; the surfing of different disciplines; the use of fiction as an expression of autonomy; concern with sustainable development and the celebration of difference and singularity.

The exhibition will map out this altermodern culturescape, presenting works by artists living in the UK, British artists living abroad and 'passers by', and includes new and specially commissioned works.

A series of four one-day events, or Prologues, are taking place in the lead up to the show, to introduce and provoke debate around the Triennial's themes.

With contributions from prominent writers, art historians, artists and philosophers, including Tom McCarthy, Jordi Vidal, TJ Demos, Carsten Höller, Okwui Enwezor and Ultrared, each Prologue will comprise lectures, performances, film and a manifesto text and will attempt to define more precisely one of the four main facets of Altermodern: the end of postmodernism; cultural hybridisation; travelling as a new way to produce forms and the expanding formats of art.