A more thorough explanation:

Definition: Field of search refers to the classification of patents into broad classes and narrow subclasses to aid in patent searches. It can also refer to any one of the several classes into which the inventions are sorted.

Examples: When searching for a patent related to a specific type of technology, such as a new type of computer processor, the field of search would include all patents related to computer hardware and software. This would narrow down the search results to a more manageable number of patents to review.

Another example would be searching for a patent related to a specific industry, such as the pharmaceutical industry. The field of search would include all patents related to pharmaceuticals, including drug formulations, manufacturing processes, and medical devices.

These examples illustrate how the field of search can be used to narrow down the results of a patent search, making it easier to find relevant patents.