To be able to patent something your idea needs to be new (novel), involve an inventive step and be non obvious. Certain countries have exclusions on things being patented such as nuclear bombs.
In general a patent will be granted for an invention as long as it is:
1. New or “novel”
The invention must not have been made in public in any way, anywhere or before the date on which the application for a patent is filed.
2. Involves an inventive step
This step must not be obvious to others with good working knowledge and experience of the subject of the patent
3. Is capable of Industrial / useful application
This means the invention must be capable of being made and used in some kind of industry.
Below are a list of things you can and can’t Patent: