Agent - a Java application that is executed on the monitored node and collects information about it. All the gathered data to be transferred to im-memory cache and than analized on the server.
Agent can monitor remote nodes as well if it is not possible to instal appliction to the host using SNMP, SQL, HTTP, TCP/UDP, Ping sensors.
To learn more about active/passive monitoring please refer to Agentful vs. agentless section.
Monitored object - a part of the infrastructure to be monitored. It can be both phisical (PC, network card, hdd) and logical (virtual machine, TCP-connection, file system) objects.
To learn more about Objects and Links please refer to Objects and Links section.