Six of Ireland’s eight universities have moved up the rankings of the world’s top universities, according to the latest global survey, with University College Dublin breaking into the top 100.The Quacquarelli Symonds (QS) world rankings compare the performance of the world’s top 1,500 universities across 106 countries.Trinity College Dublin remains the highest ranking university in Ireland, coming in at 75th for a second year in a row.For the first time in more than 15 years, University College Dublin (UCD) has entered the top 100, rising 18 places since last year to take the number 100 spot.University College Cork and the University of Galway rose to 220th and 275th in the world respectively. University of Limerick (UL) rose to its highest ever ranking at 388th globally and Dublin City University rose to 408th. They came in at fifth and sixth in the Irish ranking respectively.Maynooth University rose 50 places from last year with a QS ranking of 721-730.Rankings were based on academic reputation, employer recognition, research impact and student experience, QS said. Ireland is the 19th most represented country in Europe in the QS rankings with eight entries.The United Kingdom leads globally with 93, followed by Germany, which has 60, and Spain with 48. Ireland is one of 15 national higher education systems globally that have two or more entries within the top 100. Only 23 higher education systems worldwide have an entry in the top 100. Ireland is one of 10 European systems to feature in the top 100.Ireland is also second in the world on average in the category of employer reputation among systems with eight or more ranked institutions. Only the Netherlands has a better overall average in this indicator, worth 15 per cent of the overall results.Massachusetts Institute of Technology, in the United States, retains its title of the highest-ranked university in the world. It was followed by Imperial College London, which retained its position for a third year in a row, and Stanford University. Both are tied in second place.Ben Sowter, QS senior vice president, said Ireland last year was “home to the most-improved higher education system in Europe and this year the upward trajectory continues”. Sowter said the latest rankings “demonstrate how Ireland’s eight ranked universities are going from strength to strength in key areas such as reputation among both academics and employers, sustainability and appealing to international students”.UCD president Prof Orla Feely said she was “very pleased” with the ranking. “This represents important recognition of the success of our university in research, where we are one of the top 20 universities in Horizon Europe, in education, where the quality of our graduates is strongly valued by employers,” she said.UL president Prof Shane Kilcommins said the ranking was a “very significant moment” for the university.“This achievement reflects the deep culture of merit that defines UL, where excellence in teaching, research and student success is both expected and consistently delivered,” he said.In all, 31 universities in the UK improved on their previous rankings and 16 ranked in the top 100. The University of Oxford, Cambridge University and University College London joined Imperial in the top 10.