Dungeons & Dragons - which is now in its fifth edition - is one of the most beloved, most criticized, most played, and most argued-over tabletop RPG systems out there.
Everyone has their own opinion of what “real” D&D is. That’s stupid, because we already have an official example of Real D&D™:
If you are doing literally anything else, you are doing it wrong.
If you’re not sure about how to craft your own magical carnival ride (what insiders call a “campaign”), don’t look at the official D&D website, because it’s awful. Instead come to this thread, where millions of experienced Dungeon Masters are ready to give you expert advice on how to do things like:
Disguise the rails in your campaign so that players will think their choices matter.
Finally admit that D&D was designed with a grid in mind, and that using one makes combat easier to understand.
Ignore the rules so that you can create challenging, engaging encounters.
Figure out a way to make alignment interesting.
Learn that RP consequences are not a balancing mechanic and never will be.
Run that pirate-themed campaign you’ve been thinking about for a while that is totally not Pirates of the Caribbean.
Create your personal interpretation of Jack Sparrow for your friend's pirate campaign.
Recommend 13th Age or Dungeon World instead of D&D.