A test plan is a high level document that describes the 
objectives, scope, approach, and focus of a testing effort.

So without test plan, it is not possible to do the test.

V.Allwin.
helloallwin@gmail.com

Test Plan is the scheduler for entire Testing process. The 
Test Plan describes the approach to all development, unit, 
integration, system, qualification and acceptance testing 
needed to complete a project properly. 

Establishing a test plan based on business requirements and 
design specification is essential for the successful 
acceptance of a project's deliverables. It is important to 
note that the higher risk a project has, the greater the 
need for a commensurate amount of testing. The project 
Schedule & Task Plan and the project Staffing Plan need to 
account for testing requirements during the planning and 
execution phases of the project. 

Testing validates the requirements defined for the projects 
objectives and deliverables. Though IT project practices 
require testing throughout the execution phase of a 
project, undoubtedly the most important testing occurs at 
the end of development and prior to deployment. Orderly 
test plans that specify the criteria for test passage or 
failure are critical to a project's success.

Before we start any work....it need to be planned....who 
needs to do what,when and why
Test-plan:

similarly testplan provides you who, what, when and why ...

It provides you Test objective,scope, shedules, if 
automation tool required for conducting testing, what are 
features that need to be tested in these release,
when to stop testing, when to retart testing
Test deliverables, test methodology/stratergy,testing 
documents that need to be submitted, approvals stc.

Testplan is a document in which we can specify all testing 
related strategy we haveto follow, means what features we 
have to tested & what features we have not tested , 
hardware & software requirement, bug report , where we have 
performed automation testing , like these documents.

When we stare any thng we make plan abt that. Test plan  is 
high level doc.It's centain objective,what shold do ,what 
should not to do,steps ext.Without Test plan we cando 
anything.