Deep learning is a form of machine learning that uses a model of computing that’s very much inspired by the structure of the brain.
With the help of deep learning, we are trying to mimic the human brain. We are trying to train the machine the way human brain thinks and works.
To get better understanding of how does machine learning works, we need to first understand how human brain works.
The brain works with the help of brain cells which we called as neurons. Neurons has dendrites which receive signals from other neurons. The cell body which is surrounded by the dendrites receive all the signals and summed them and forward these signals to axons. With the help of axons these signals are fired to the next neurons. The next neuron is present at some distance and that distance is known as synapse. It fires only to the next neuron when the signals coming from cell body exceeds a particular limit.
By copying the same process we can create artificial neuron and it does the same function as the brain does. Read more about Machine Learning Algorithms: When To Use Which Machine Learning Algorithm