SDLC is Software Development Life Cycle. It is the process by which Information Systems or Software are developed and designed. Like every other process, SDLCs have various methods to complete the steps. One of the oldest ways to go about is the Waterfall method. The first known usage of Waterfall was in 1956 by Herbert D. Benington at Symposium on advanced programming methods for digital computers. This 57 years old format has been behind the formations of countless projects in so many industries overtime but it was continuously challenged by other SDLCs that arose out of necessities like faster working and less required documentation. One of the major competitions that Waterfall method faces is the Agile Method.
The waterfall method goes through the phases of Conception, Initiation, Analysis, Design, Construction, Testing, Production/Implementation, and Maintenance one after the other like the motion of a waterfall. The team cannot move on to a phase till the previous phase is complete. The positive thing about this method, even though it is time consuming, is that if the bugs are found early on it saves a lot of time and money later. For instance if a bug is found in the conception or initiation phase then it can be corrected before going to the design phase rather than it being discovered while the software is getting designed and then has to be scrapped completely. This method requires intensive documentation in each phase and in that way the process is not dependent on any individual on the team. If a component of the team needs to be replaced, the new person can understand where the project is currently, easily.
The Agile method on the other hand is an iterative and incremental approach to software development. In this form of SDLC small modules of the final products are released for the users to review and then are changed accordingly. As per the name, this environment is flexible and can be changed according to the circumstances. Here different developers work on their own task simultaneously and then combine their work in the end. The focus is on delivering a working software rather than documentation. Since it’s iterative, that means it works in cycles. New things are discovered during each iteration and then can be improved upon or fixed before the next cycle begins. Communication, rather than documentation, is used and as such it is faster to work in an Agile environment. Agile methods seem best for developmental and non-sequential projects; as such they are ineffectual in some types of projects and is not taken seriously by a lot of companies.
Both these environments exist in the IT world right now. They are flourishing side by side and both have their respective pros and cons. One cannot say which is better than the other and they should be used ideally according to the suitability to the Project in hand.