The reason I put this next on the list is because you can plan your dining up to 180 days out from your trip. This may seem like an unnecessarily long time, but depending on the restaurant you have your heart set on, you may need to wake up early to book your reservation (more on that later).
There are many (and I mean MANY) different dining options at Walt Disney World. There are a few different types of restaurants: quick service, table service, character dining, buffet, and dinner shows. All of these vary in price. You can find dining at all resorts and theme parks.
Quick Service: This is a sort of counter style dining option. You order at a cashier, and then move forward to pick up your food and find yourself a table. Kind of like eating at a fast food restaurant. Cheapest option. You don't need reservations for these. You can find these at every park. The resorts will also have market-style areas where you can buy pre-made items like salads and sandwiches. Some of the value resorts also have "food-court" or "cafeteria" style restaurants where you have a tray and pick what you want from the selection that is offered.
Table Service: Self-explanatory. You're taken to a table where a waiter takes your order and brings you your food.
Character dining: Also self-explanatory. A table-service restaurant that has different characters walking around and interacting with the patrons at their tables. Popular ones include: Cinderella's Royal Table, Chef Mickey's, Akerhus, 'Ohana, Garden Grill, and Crystal Palace. Different characters are at each restaurant so find your favorites! Some have princesses, while others have classic Disney characters. Some of the restaurants only have characters for certain meals, so be sure to check!
Buffet: No need to explain. Some of the character dining experiences are buffets.
Dinner Shows: Dinner and a show :) There are a couple of these around WDW. Mickey's Backyard BBQ, Hoop-dee-doo Musical Review, and Spirit of Aloha.
I've had many people ask me "Do I really need a dining reservation? Can't I just go to a restaurant when I get there and ask for a table?"
You can. BUT you may be told there are no available tables left for the night, or that you will have to wait a ridiculously long time before a table is ready. You could get lucky but the odds are against you. You can then just head over to a quick-service restaurant.
If you are wanting to eat at any of the following restaurants, I would highly suggest trying to make a dining reservation ASAP!:
Victoria and Albert's
Cinderella's Royal Table
Be Our Guest
Chef Mickey's
Akershus
California Grill
'Ohana Dinner
Le Cellier
Fireworks Dessert Party
Fantasmic Dinner
And what do I mean when I say wake up early? At your 180 day mark, 6am (ET) is the time reservations go live. Now, if you tried to make your reservation and nothing was available, don't fret! People cancel all the time, so just keep checking back and see if anything opens up down the line.
On a budget? Stick to quick-service meals and bring in snacks instead of buying snacks at the parks.