Deep Learning needs a lot of data yet Traditional Machine Learning needs much fewer data points to train.
Neural networks have 3 types of layers: input, output and hidden layer.
CNNs are good at computer vision tasks.
Weight and bias are the two main parameters that are learned during training.
To be able to calculate the output of the network simultaneously for all the data points. This makes the network faster.
Because otherwise, the network is just a linear transformation of the inputs. And no matter how big the network gets it will be as good as a single neuron because of this linearity. This will cause the network to not be able to fit complex data.