In order to orchestrate and deploy to servers, BuildMaster needs to be able to communicate with those servers in an fast and secure manner.
Communication with Windows servers is generally accomplished using a lightweight agent that's installed on the remote server. This agent uses a highly-optimized and resilient protocol built solely for this purpose, and is quite easy to install.
Alternatively, BuildMaster can use PowerShell Remoting to communicate with Windows servers; however, this is generally slower and less resilient than the Inedo Agent protocol. You can connect using integrated authentication (i.e. whatever account the service is running under), or with a username & password resource credential. See Enable-PSRemoting to configures a server to receive remote commands.
To communicate with Linux servers, BuildMaster uses the lightweight, highly-optimized, and resilient protocol already enabled on nearly every Linux box: SSH and SFTP. You can connect with a private key or username & password resource credential.
If you're using BuildMaster to interact with the server it's installed on, you can just set it up using a local agent. This uses the same process/identity that the service is hosted as, and doesn't have very many privileges by default.
In BuildMaster 5.0 and earlier, a different agent model was used; to learn more about these, see KB#1039: The Inedo Agent and Legacy BuildMaster Agents.
Server are the core of your infrastructure and being able to easily manage configuration and orchestration is key to modern, scalable environments. A server represent a physical ("bare metal"), virtual server, a container, or even a yet to be provision server.
BuildMaster gives you the ability to see at-a-glance the status and environment of each server.
Server roles in BuildMaster allow you to targets a group of servers in a pipeline stage, or iterate over them in deployment plans.
In Legacy Plans, the Server Groups feature enabled actions or action groups to target of multiple servers. They are hidden from the UI unless you have any Legacy Plans configured.