Don't Forget about MagicBands!
You may want to consider purchasing a MagicBand for convenience. If you set up a My Disney Experience account and have valid theme park admission you can use a MagicBand instead of the plastic theme park card.
A MagicBand will allow you to:
Enter theme and water parks (with valid park admission linked to it)
Check in at Fastpass+ locations
Connect Disney PhotoPass images to your account
The card you are given will have the same functionality as the band some people prefer the convicne of not having to take the card out to scan for FastPasses etc.
If you are not staying at a Disney Resort hotel you will receive a card, similar to a plastic credit card, when you purchase your theme park tickets. This card has all of the same functionality as the MagicBands, however you may chose to purchase a MagicBand for convenience.
If you are not staying at a Disney Resort hotel, or would like a decorated MagicBand you can purchase them:
Select Disney Springs retail locations
Select Walt Disney World theme park and Resort hotel retail locations
Linking your theme park tickets to your MagicBand
Once you purchase a MagicBand you will need to link your theme park tickets to your band (you do not need to do this with the complementary bands that Disney sends you if staying at one of their resort hotels).
To link your park tickets to your MagicBand you will need to have a My Disney Experience account. You can follow the steps to link your MagicBand here