Hi Murali

Indian Army is called lifeline of the security of Nation . One can join army anytime with any qualification, i.e. after 10th, 12th, degree, diploma etc.

You can join Army after 10th-12th through NDA. 

Educational qualification for army wing of NDA : pass certificate in class 12 exams via recognised board or a university.

For more details about qualification, physical Eligibility and other necessary information visit NDA website.

If you are between 16-18 years old then you can apply for NDA.

You have to clear SSB interview for NDA and you'll have 2 years training, and after completing your training you will joining the forces. 

You have to give UPSC exam. If you qualify that then you'll go through a process of SSB interview. After passing that if your name appears in merit list then you can join NDA

If you are a graduate you can go for CDS And SSB. 

If you crack CDs Examination you will be called for SSB interview and Various other screening tests.

You will get 2 choices : 1. IMA 2. OTA

NCC special entry:

If you are NCC cadet with 2 years service in NCC senior division army. Then, final year student/graduate is also Eligible for this entry.

TCG (technical graduate course entry): only engineering students are eligible for TCG.

TCG is permanent commission.

SSC: same as TCG.

SSC is short service commision ( difference between TCG and SSC)

SSC JAG entry: this is for law graduates. You must be having minimum 55% aggregate and must be registered with bar council of India.

There are complex streams and different eligibility criterias for them. It is not possible to cover everything, so you can obtain necessary information from Army recruiting office, and other websites.

For now, you should fulfill all the necessary requirements to meet all the selection standards. You should work on your physical, educational, medical and other qualifying criteria and selection standards.

All The Best!!