How is the traffic measured? What are the types of traffic , if any?

Measured traffic is either inbound or outbound, sometimes both ways.
Everything that is communicating with your server/service is measured in some way.

Traffic means "Data Transfer", which itself stands for the transfer of data on top of a communication channel (Internet connection).

In web hosting, traffic means the visitors coming on your website. The traffic is measured in terms of bandwidth. The bandwidth is allotted to you in your web hosting plan. So, the amount of bandwidth allotted can handle only that much visitors on your website.

If you have large amount of visitors on your website, you should consider unlimited hosting plans that offer unlimited bandwidth.

"Unlimited traffic" such a thing does not exists because of network's hardware limitations. That's this epuipment that will record server's traffic, generaly it is centralised under one interface. If the information is relevant and available, customers can find it on their customer portal. For individual websites or individual application measures; it is up to customer to setup tools that will give them infomations about visitors and users.

Traffic means vistiors on site or user/process on server that consumes

resources(bandwidth) of web hosting accounts(that are shared, VPS or

dediacated)