Hydration
What is considered hydrating? Water! Tea, especially herbal teas, without caffeine. Caffeinated drinks, like coffee can be dehydrating, but only slightly. It does not take more hydration out of your system as it takes in.
Fruit has a lot of water but it is considered food because of its nutritional content. Watermelon is 95% water, so you might say you replace some water while having some.
Real fruit juices are considered food, but a half a cup is plenty. But they are just weak shadows of their flesh and blood real fruit counterparts. When you need to chew, and you you digest the whole fruit, you have the whole experience!
Milk is considered food as well. It provides protein, calcium, vitamin B12, vitamin A, potassium, magnesium selenium and phosphorus.
Fruit drinks, either from concentrate or diluted are considered food or sugary drinks. They pack up calories and do not match their real fruit counterparts!
Pop, soda sugary drinks are NOT considered hydrating, they are full of empty calories and need to be avoided.
Alcohol is the most hydrating! For 7 calories per mg, you are not getting any nutrition, only drying out your system.