Describe the steps of  Backpropagation  learning algorithm in artificial neural network (ANN)

Backpropagation learning algorithm in Artificial Neural Network (ANN) involves the following steps:

1. Initialization: Initialize the weights and biases randomly for all the neurons in the network. This is to ensure that all neurons have different weights and biases to start with and learn different features of the input data.

2. Forward Propagation: Each input is passed through the network, with each layer of neurons applying their weights and biases to the inputs and passing them through an activation function. The result is the final output of the network.

3. Cost Calculation: The output from the forward propagation is compared with the expected output, and the difference is used to compute the cost (or error). The cost function could be Mean Squared Error, Cross-Entropy, or any other function that can measure the difference between the actual and the predicted output.

4. Backward Propagation: The error computed in the previous step is then propagated back through the network, starting from the final layer. This is done by taking the derivative of the cost function with respect to each weight and bias in the network. This gives the gradient of the cost function at the current point.

5. Weight and Bias Update: The weights and biases are then updated in the direction that reduces the cost. This is done by subtracting the gradient of the cost function from the current weights and biases. The size of the step taken in the direction of the gradient is determined by the learning rate.

6. Iteration: Steps 2-5 are repeated for a number of iterations or until the network's predictions are good enough. The number of iterations can be a fixed number, or it can be determined dynamically based on the improvement in the network's predictions.

7. Evaluation: Finally, the performance of the network is evaluated on a separate test set to ensure that it has not just memorized the training data but can also generalize to new, unseen data.

Remember, the goal of backpropagation is to minimize the cost function, and it does this by adjusting the weights and biases in the direction that causes the most rapid decrease in the cost.