You've already identified the two most common ways. Unfortunately, there is no reliable way to know if the same person has already seen your site. For example, in an office one public IP address may be used by dozens (or hundreds) of people. Yet, if you set a cookie, if two people in the same household use the same browser, you only get the first person.

Also, people can block cookies. In large organizations, or on some public networks, the public IP address may change in mid session.

javascript - How to detect a unique visitor is unique? - Stack Overflow

as has already been described up here, the most commonly used methods are using IP address and cookies. Both have their downfall. In the case of an IP, an office sharing the same IP can be your pitfall. I would go for cookies straight away.

I will create cookie with some basic information which I will check for once the user tries to access my website. I know the can delete cookies but I consider that as a remote thing that normal visitors do.

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