The University of Oxford (informally referred to as Oxford University or simply Oxford) is a collegiate research university located in Oxford, England, United Kingdom. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096, making it the oldest university in the English-speaking world, and the second-oldest surviving university in the world, after the University of Bologna. In post-nominals, the University of Oxford is commonly abbreviated as "Oxon.", from the Latin Universitas Oxoniensis. Since 2007, "Oxf" has been used in official university publications, though this "has been criticized by some readers".