HTTP is the fundamental protocol of the World Wide Web. HTTP is a connectionless request response protocol, meaning there is no concept of a persistent connection between a series of requests.

REQUEST AND RESPONSE

An HTTP request is a message sent from the client to the server. The server sends back a response. The request and response might contain content called the body. In addition, the response always contains a numeric response code, which lets us know if the request was successful. It gives more detailed information about what exactly happened (e.g. the cause of failure).

METHODS

HTTP supports several request methods, which help the server know how to handle the request. The HTTP methods for our purposes are:
GET: Used to retrieve a resource (such as a web page or image) from a URL
POST: Used to send data to a server (such as the content of a form) based on a URL

HEADERS

Finally, in addition to the main content of the request and response, HTTP allows additional data to be sent in the form of headers. They can be sent with the request to the server and the response from the server, and they can contain arbitrary text data. There are many standard headers, and the connection API contains methods for easily accessing some of the most common ones.

FileCloud records all API calls in the audit log, therefore, authentication cannot be done with an API token.

When you log in with loginguest or adminlogin and provide the correct password, the server creates a new session, and returns the authentication parameters in cookies which are included in all subsequent calls. The cookies allow the server to link your API call to the existing session.

More details about cookies can be seen in these examples:
Curl/Bash Sample: File Upload and Download - cookie is stored in the file ${USER}_cookie.txt
PowerShell Sample for FileCloud API - cookie is stored in the variable $LoginResponse.Headers['Set-Cookie']