Disney Magic is all the things you have ever read or seen on TV and in Movies in a real place.
I grew up in Florida watching the Wonderful Word of Disney and the Mickey Mouse Club on TV and through the years remember all the milestones and expansions that Disney Imagineering has put into place.
When you stay on property there is a sence of fantasy and "Magic" as the CM's try to make your stay as awesome and enjoyable as can be.
The subtle music, to noises and sights and sounds of the parks and all places in between. The special treats that Mouse-keeping leaves behind.
The way Disney was designed to hide all the hustle and bustle of running a park so that only the fun and excitement is visible.
The Magic is that feeling you get when you step off the Monorail or hear the warm greeting of the CM at the Welcome Desk at your resort.
When they hand you your Keys to the World and tell you it gets you into all the parks and your hotel and it is your card for Dinner. (Park hopper and Dining plan required

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There is no ending definition to the Disney Magic, all you have to do is Believe and Seeing is Believing!!!
M-I-C...See ya real soon.
K-E-Y...Why? Because we like you.
M-O-U-S-Eeeeeee.