If the wizarding world had WI-FI.
If the wizarding world had the internet, Harry, Ron and Hermionie could have just put Nicholas Flamel in to google and Bam! they could have got to the stone weeks before Quirrel. They could have just googled the Chamber of Secrets and found out about the Basilisk without having to follow the spiders. Harry could have put Serious Black into google and known who he was as quick as he could say Buckbeak. Harry could have Googled How to breath underwater for an hour, or plants/ spells that allow you to breath underwater and he wouldn’t of had to worry about staying up all night before the second task. Harry could have Skyped Sirius to see if he was at home instead of being tricked by Kreature, so then he could have had back up when he went to the ministry and Sirius might not have died. Harry could have just Googled Horcruxes and known what they were from the begging of the school year and they could have just Googled The Deathly Hallows instead of having to spend a long time camping in the middle of nowhere. They would have had lives that were a lot simpler.
Then again, the books wouldn’t have been as interesting if all they had to do was Google it and the problem was solved.