purely online chess is only a starting point to chess enlightenment!

I think more would agree than disagree with me that if your chess adventure has only ever been invested on any of the on-line chess sites your chances of making real progress and understanding in all three phases of chess 1.)Opening 2.)Middle Game, 3.) Endgame are not likely if you are only playing online, the reason for this is 70% of pure online chess players usually only play either Blitz or Bullet and there Middle games and endgames will not improve to a decent standard The only real way to improve those Area's is by checking your local Area where you live for a local over the board chess club, here you will get all the one to one coaching in those Area's of play needed to become a good player!

If all you do is blitz and bullet online, your chess growth will likely stall.
If you want to truly improve, especially in middlegame and endgame understanding, playing slow games (ideally over-the-board) and reviewing them with others is essential.