What is Keras.Sequential() and why we use it and is there any other option other than using Sequential model?

[ashikshafi08]

There are two ways to build Keras models:

Sequential and Functional

The sequential API allows you to create models layer-by-layer for most problems. It is limited in that it does not allow you to create models that share layers or have multiple inputs or outputs.

Alternatively, the functional API allows you to create models that have a lot more flexibility as you can easily define models where layers connect to more than just the previous and next layers. In fact, you can connect layers to (literally) any other layer. As a result, creating complex networks such as siamese networks and residual networks become possible.

You will learn Function API later in the course.

If you want you can check the detailed explanation in this Stackoverflow thread.