What is Non-ECR category in passport and what is the elegibility criteria?

ECR stands for Emigration Check Required and ECNR stands for Emigration Check Not Required(Non ECR).
you are eligible for Non ECR category if
1.All persons having educational qualifications of matriculation and above.
2.All holders of Diplomatic/official Passports.
3.A GAZETTED Government servants.
4.All income-Tax payers (Including Agricultural Income-Tax Payees).
5.All professional Degree holders, such as Doctors hoiding MBBS degree or equivalent degree in AYURVED or HOMEOPATHY, accredited Joumalists, Engineers, Chartered Accountants, Cost Accountants, Lecturers, Teachers, Scientists, Advocates, etc.
6.Spouses and dependent children of category of persons listed from (2) to (4)
7.Persons holding Permanent Immigration Visa, such as the visas of UK, USA and Australia. Persons possessing two years diploma from any institute recognized by the National Council for Vocational Training (NCVT) or State Council of Vocational Training (SCVT) or persons holding thre years diploma/equivalent degree from institutions like Polytechnics recognized by Central/State Governments.
8.Nurses possessing qualifications recognized under the Indian Nursing Council Act. 1947.
9.All persons above the age of 50 years.
10.All persons who have been staying abroad for more than three years (the period of three years cou be either in one stretch or broken) and their spouses. 15 All children up to the age of 18 years of age. (At the time of re-issue at the age of 18 years, ECR stamping shall be done, if applicable)