An organization to develop an application they follow the certain rules and regulations to develop software application rules and regulations are described proces is SDLC. it contains 6 phases 1. business analyst gathers the requirements from client and prepare the brs document. and product management team will prepare the snap shots based on the requirements.
2.based on the brs documents pm and tl prepare the hld and lld design documents.
3.based on the HLD AND LLD developers develop the actual source code.
4.if the build is ready and stable then testers will do the test the functionalities of an application.
5.after the completion of testing qa and product team push the application into production side.
6.after the product is deployed developed company will maintain the product for a particular duration.
Every Company that creates SW follows a SDLC but we all know they are all are not the same from company to company. Some may follow the traditional waterfall and others follow Agile or Lean. Since this question is open ended the logical answer would be all phases of the SDLC is of equal importance. The art and science behind releasing a quality product will depend how each company will able to handle the risks at each phase of the SDLC.
requirement phase is very important bcoz w.r.t the application requirements nly we need to test the appliocation from design phase to release phase hence analysis of the requirement given by the client should be verified thoroughly.
SDLC Software Development Life Cycle is a systematic way of developing a software product/Application using some company based standards and models. It has different phases and each phase is a base for the next phase and every phase is important one.
These phases are
Software Initiation Phase Company Project Managers Business Analysts Leads etc peoples make some initial plans for the proposed project based on clients requests and demands budget cost resources etc.
Requirement and Analysis Phase BA and Leads will collect business requirements what system is going to do what its not supposed to do what are real end user wants etc kind of things are gather and made as business requirement/specifications. This requirements are possible or not/ feasible or not etc. What are SW/HW requirements what are resources and etc
Design Phase
Team Leads and Architects will design the system High level design they will make and developers make Low level design documents Define how the system should be like the Database design network design etc.
Development Phase SW developers and other analysts develop the code in any programming language or SW. SW Coding is done here
Testing All the QA people test the developed code in different testing methodologies and testing types and find bugs and communicate the defects to the team and make sure the defects got fixed and retests them. And ensure the system is bug free.
Implementation and maintenance/Development and maintenance phase System is moved to the production or to the real users. for the customers and if any additional requirements are added or system is upgraded then all the people will work on that issue and implement it and maintains the system.
Each and every phases is very important in SDLC. If initial phases Requirement Gathering and Analysis System Specification is clear cut then all phases could be simple
1 
0