What are the levels of monitoring and their importance?
In our environment we use Appdynamics and logz.io for all levels of monitoring and it's a best tool,

Basically it monitor it for all levels,


Databse
Application especially works well on Java based services
Servers, containers
remote services
Business transactions
service endpoints, etc.,


Also it monitors all the components like, CPU, Memory, Load average, Network errors per minute, Network utilization, top 10 process usage of CPU and Memory.

All monitoring you can get it in the graph format.