Whether add bias or not in a perceptron

In some places, perceptron is described as having added bias, while in some places, bias is not added.

Which one is right for you?

Suppose bias as a threshold. Using threshold, your activation function moves across the $x$ axis which may get complicated. Consequently, people usually use the bias term and always centre the activation function which is the step function at zero. There is nothing wrong in both cases.

• Thanks, Do you have a website that I recommend to learn artificial neural networks? – Developer Aug 2 '18 at 10:12
• Good beginning point can be Pr. Andrew Ng's course on deep learning. Take a look at here which contains everything you may need. – Media Aug 2 '18 at 10:15