How does the patent office examine patents?

Computer retrieval combined with manual photography, words with the same or similar technical characteristics, scientific names, trade names, chemical names, common names, etc. You can use "or" to search, such as "speed" and "sodium bicarbonate" (baking soda, baking soda). Because patent applications are similar to "eight-part essays", auditors read many patents and are also one when examining them. Such as food, chemical industry, medicine, textile, machinery, etc. It is impossible for food auditors to examine machinery patents), and determine "keywords and retrieval types by virtue of their familiar professional fields. All by hand, it will be crazy.