An Activation Function decides whether a neuron should be activated or not. This means that it will decide whether the neuron’s input to the network is important or not in the process of prediction using simpler mathematical operations.
The role of the Activation Function is to derive output from a set of input values fed to a node (or a layer).
Use softmax for multi-class classification!
The loss function is a method of evaluating how well your machine learning algorithm models your featured data set. In other words, loss functions are a measurement of how good your model is in terms of predicting the expected outcome.