there are 5 phases in sdlc:
1)requirement & analysis
2)design
3)coding
4)testing
5)maintainance

1)requirement & analysis:
  the main aim of requirement analysis phase is to produce 
a document that properly specifies all reuirements of the 
customer.
 requirement specification document is the primary out put 
of this phase.
  proper requirements and analysys are critical for having 
succesful project.
  the need for executing this phase properly to produce an 
srs  with the least defect should be evident.

2)design: during the design phase the user requirements are 
elicited and software satisfying these requirements are 
designed built tested,delivered to the customer.

 high level:high level design is the phase of life cycle 
the logical view of computer implementation of solution to 
the customer requirements are developed.it gives the 
solution at high level of abstraction.during the high level 
design the functional architecture of application and 
database design takes place.
 the entry criteria is that srs has been reviewed and 
authourised. the input for this phase is software 
requirement specification and output for this phase is high 
level design document. the exit criteria is that the high 
level design document has been reviewed and authourised.

low level design:the view of the application developed in 
the high level design is broken into modules and logic 
design is done for every program .a unit test plan is 
created and documented as program specification. the 
important activity in the detailed design phase is 
identification of common routines and programs.

the entry criteria is that the highlevel design document 
has been reviewed and authourised.
the exit criteria is that the program specification 
document has been reviewed and authourised.

coding:
during the coding phase required programing language is 
used to produce the program.this phase produces source 
code, executables and database design.

testing:
here actual testing takes place .

maintainance:
succesfully developed project will undergo for maintainance.

explain SDLC:
             SDLc are 5 stages
               1.Analysis phase
               2.Design phase
               3.coading 
               4.testing
               5.release & maintaince
Analysis phase: In my opinion analysis phase is most 
Importent in every ptoduct .
                 At the analysis phase stage the customer 
will analyse:
                1.need of the project
                2.cost of the project
                3.what are the benfits and advantages of 
the project
                4.Identify the requirment
                5.Identify the scope of the project
                6.agrement with any development company to 
develop the software
Note: At this stage the development company also analyse 
the cost of the project resource required,technolagy to 
develop the s/w and get the agrement with development 
company
             The fallowing documents sre prepared at this 
stage
                1.NDA (NON disclosive agreement):
                   It should fallow some rulles and 
regulations
                2.SLA(service Level agreement).This 
document contaains the services to be provided by the 
development company to this customer
              3.BRS (buisiness requirment specification):
                       This document contain overall 
functional details about the s/w
                     NDA,SLA are prepared by managers of 
development company and customer company,approved by both 
company
            BRS document prepared by Buisiness analyst
4.Project plan:
                 This document has the overall shedules of 
the project,cost,resources etc.It is prepared by project 
manager
5.FRS/FRD:(Functional Requirment specification or document)
    
This document about detailed information about all the 
requirments.This document prepared by buisiness analyst.

6.Software requirment specification:
                         It contains Software requirment 
details like front end technolagy,backend 
technolagy,operating systems,Hardware architecture of the 
project are described
                And then go to design phase
After analysis the development will prepare the design 
phase for the project
                the design is prepared as per requrment.The 
design for frontend based on the HLD ,LLd,Dtabasedesign.

HLD means (High level design):
                 It explain main modules of the project
LLD means (Low lwvwl design):
              It explain all the details of the operands etc

and then goto coading:

After design approved the development team will design the 
code and write the code.

and then goto testing:
                  After coading is done the application is 
tested to ensure it is working as per the requirment .
                testing is conducted by developers,testing 
team,users at different stages
and then goto Realease & Maintaince::

After testing is completed the s/w is released to the 
cusomer,After released maintaince is the for any issues in 
the s/w.
            :This is the s/w Development Life Cycle: