Short Definition
Dropout is a regularization technique that randomly disables parts of a neural network during training.
Intuition
By preventing units from relying too heavily on each other, dropout pushes the network to learn more robust representations.
Technical Definition
Dropout samples a binary mask over activations during training and rescales activations so inference can use the full network.
Example
A feed-forward classifier may drop 20 percent of hidden activations during training to reduce overfitting.
Common Misunderstandings
Dropout is usually disabled during inference.
Dropout is not a replacement for good validation or data hygiene.