*UPDATE: JANUARY 2021* DISNEY DINING PLANS ARE CURRENTLY NOT AVAILABLE TO BOOK, BUT I WILL UPDATE AGAIN ONCE THIS CHANGES.
Not everybody will want to use the Disney Dining Plans as they are not for everyone, but here is a little bit about them and how we used ours last year.

Mickey Pretzel! 
Tony’s in Magic Kingdom 
Hollywood & Vine, Hollywood Studios 
Paradiso 37, Disney Springs
There are 3 levels of Dining Plan: Quick Service Dining Plan, Disney (mid-level) Dining Plan and Deluxe Dining Plan. For each plan, per person, you get a certain number and type of credit:
These are either Quick Service (QS) credits which can be redeemed at Counter Service restaurants, Table Service (TS) credits which can be redeemed at Table Service and Signature restaurants (Signature dining usually require 2 TS credits) and Snack (S) credits.
Quick Service = 2 QS credits, 2 Snack credits per person per day.
Dining Plan = 1QS credit, 1TS credit, 2S credits per person per day.
Dining Plan Plus = 2TS credits, 2S per person per day
Deluxe = 3TS credits, 2S credits per person per day.
All four plans also include one non-alcoholic beverage (under 21) or alcoholic (over 21) drink per meal entitlement AND a refillable mug to use in the resorts ONLY.
Note: Tips are NOT INCLUDED. You will need money for these.
Some of the snacks are not small. You could make a pretty decent meal out of your two snacks so we most often used our snacks for breakfast early before heading into the parks, with a drink with our refillable mugs. Then we had our credits ready to roll for our other meals. Or sometimes we used the QS meal for a mid morning brunch and the TS credit for a later evening dinner. This is especially handy if you’ve got the plan but aren’t spending the day at a Disney park!
These credits, once you have them though, can be used in ANY combination throughout your stay. So for example, in the Standard Dining plan, you get 1QS, 1TS and 2S per person per day (techinally per night,) so if you are staying for 14 nights, you get 14QS, 14TS and 28S. So, if you wanted to you could use 3 table service credits in one day if you wanted. You would be full and probably wouldn’t be able to move in the parks, but you COULD do it!
If you are more of a video person, here is a great and very helpful video on the Disney Dining Plans from Disney Food Blog Guide and here is an EXCELLENT list of which restaurants use what credits (and if you’re not on the plan – how much the meals will cost you! – from WDW PrepSchool.
Another tip I’ve picked up is to set aside the amount you would spend on a dining plan onto a pre-paid card, or for me, it’s going into one of my Monzo bank account pots, then only buy food and drink from there. This will give you a really good idea of how much you spend on food while at Disney and then also when/if you have some money left over, you can just put that into your spending for merchandise or (maybe not!) bring it home again! Can you imagine bringing money BACK from Disney??