I brought home a tomato this morning (one of the smaller of my Rose de Bernes, which have been producing beautifully) which provides a classic example of sunscald, so I thought I'd share:
Sunscald (you can read more about it here) is the result of a fruit being exposed to prolonged direct sunlight, especially under the hot conditions we've been experiencing. It occurs in tomatoes, peppers, melons, squashes, and other fruits. Appearance can vary from discoloration to pale blistering to (if caught late) rotting.
We get a lot of questions at this time of year about fruits damaged this way, and it's easy to conclude that a disease or insect is at fault - but always remember that at least half of the problems you see in your garden are caused by environmental issues or other abiotic (non-pest-related) problems. Sunscald usually occurs when a plant is partially defoliated, for example by early blight in tomatoes, which we're seeing a lot of this year. You can help prevent it by keeping your plants healthy so the leaves will shade the fruit.
In this case, one of the branches of my plant wasn't sufficiently tied up, and fell to the ground, exposing the fruits to far too much sun. Usually the fruit is too spoiled to eat, so this one will be added to my compost.