Some ideas covered in the Software as a Service course conducted by edx are discussed here. The first week of course covers some basic software engineering concepts. Software and hardware, the two basic components of any system differs in many ways. Hardware is developed completely before it is being delivered to the vendor. If any error occurs after the delivery of the product, the only solution is to replace the whole hardware. But the situation is different in case of a software. Software evolves over time and if there occurs any bug, it could be easily cleared with some updates to the software. Software can be categorized as legacy software and beautiful software . Even though legacy software satisfies the end user, it remains the same over time and is difficult to evolve. But beautiful software is easy to evolve as well as meets the customer needs. The various software models to be discussed here are Waterfall model, Spiral model, Agile model . Water fa...