An invention relating to a product or process that is
New,
Involves an inventive step, and
Is capable of industrial applicability.
Frivolous inventions, contrary to law, morality, or public order;
Pure scientific discoveries or abstract theories;
Mere mixtures of known substances, or the mere arrangement or re-arrangement or duplication of known devices;
Methods of agriculture or horticulture;
Inventions based on traditional knowledge;
Methods of medical treatment or diagnostics;
A mathematical method or business method or computer program per se or algorithms;
Mere discovery of a new form of a know substance, new property, or new use of known substances (unless showing enhanced efficacy); and
Inventions related to atomic energy.
For a complete list of inventions that are not patentable in India, please see link
The Indian Patent Office (“IPO”) accepts the following types of patent applications:
Ordinary Application (which includes a provisional application and complete specification),
Convention Application,
PCT International Application,
Divisional Application, and
Patent of Addition.
Patent Cooperation Treaty (PCT): India has a 31 month due date for PCT National Phase filings; and
Paris Convention: A priority claim is possible within 12 months from the earliest filed home country application.
See below for the major steps:

Proof of right to file an application from the inventor(s);
Patent specifications with claims and necessary drawings;
Information related to foreign patent applications with respect to the same/similar invention;
A declaration from the inventor(s) stating they are the true and only inventor(s) of the invention;
Original signed Power of Authority from the applicant in the name of agent(s);
A priority document if relevant; and
Certified translated documents where any of the above documents are not in English.
There is a reduced official fee for the following types of applicant(s): natural persons, start-ups, small entities, and educational institutions.
3 to 5 years.
A patentee enjoys the exclusive right for 20 years from the date of filing or priority, whichever is earlier.
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