(1) Encourage innovation, including scientific research innovation of schools and innovation of employees in R&D..
(2) Protect the intellectual property rights of companies or units, and prevent others from stealing others' innovations for defense.
(3) Fight patent wars, such as Google's acquisition of Motorola and Microsoft's acquisition of Nokia. A large number of them want to collect their patents. When you have enough patents, you can fight patent wars to protect yourself. Perhaps the most famous is the patent war between Apple and Samsung.
(4) advertising. Patents are a good means of publicity. Many companies like to detect the patent trends of other companies, which is actually a research and development or future trend.
(5) Patent monopoly, which is most obvious in Qualcomm. You may have to pay a patent fee to Qualcomm for each smartphone.
(6) patent transfer. Many companies or individuals apply for patents in order to transfer patented technology and profit from it.