During the search, if you encounter granted patents/patent applications which are disclosing the novel feature/features of your invention, it implies that the invention is already patented, and your invention is not patentable.   Similarly, there are many such inventions/ideas/documents which are never patented but are present in the public domain. These documents act as prior arts, and the current invention will not be patentable.   Further, to identify if a product has a patent, one needs to identify the assignee of the product. Next, go to a database or Google Patents and search for the portfolio of the assignee. If the number of patents in a company portfolio is less, they can be each analyzed to identify the patent for the product.   However, if the company portfolio is quite large, search key strings using keywords or elements for the product features have to be searched to output and analyze a doable number of hits. One can also go through tile, abstract or claims of the patents to analyze the citation in less time, since the novelty of an invention is claimed, and one can identify a relevant patent after analyzing the claims.   In addition, there are various laws that are taken into consideration while performing patent search. These laws are subject to jurisdictions. These laws are based on novelty, obviousness and usefulness of an invention.