Transfer window: When it was introduced, dates & everything you need to know Unknown 04:12 Goal brings you all you need to know about what has become a key fixture in the calendar of football across the world Share this Share on FacebookTweet on TwitterPlus on Google+ Related PostsBernie Ecclestone slams 'prudish' decision by Formula One to dispense with 'grid girls'India Open 2018: Kidambi Srikanth falls to Iskandar Zulqarnain's strong defence; PV Sindhu, Saina Nehwal win easilyISL 2017-18: Bikash Jairu's late strike propels Jamshedpur FC into top four with win over Mumbai City FCCopa del Rey: Luis Suarez gives Barcelona edge over Valenica in semi-final first leg; Leganes draw against SevillaSt Petersburg Ladies' Trophy: Caroline Wozniacki races into quarter-finals; Kristina Mladenovic ends losing streakPremier League: Mesut Ozil confirms future at Arsenal, signs new three-year deal