For each of the ports within our database we attempt to provide you with a meaningful risk value, this can be especially helpful when you’re trying to judge what the impact to your network is by carrying this traffic.
The level is based on the possible security risk that a specific application may have, examples of this would be an application like a proxy which is generally there to evade and avoid firewalls and network security, or tools like bit-torrent that are often used to transfer illegal file contents.
However, these are only a guide, for example HTTP and HTTPs are one of the most commonly used protocols on the internet, however these are also both used for some very risky and malicious activities.