"ELK" is the acronym for three open source projects: Elasticsearch, Logstash, and Kibana. Elasticsearch is a search and analytics engine. Logstash is a server‑side data processing pipeline that ingests data from multiple sources simultaneously, transforms it, and then sends it to a "stash" like Elasticsearch. Kibana lets users visualize data with charts and graphs in Elasticsearch.
How effective is ELK than other Monitoring tools?
ELK is pretty ineffective as a monitoring tool in a default configuration as it doesn't do monitoring - only reporting. ELK can only provide monitoring and alerting abilities if you configure additional add-ons such as ElastAlert.
Then, you are impacted by your ability to log errors via syslog. If messages come in via, say, SNMP traps, you will be unable to alert on these if you do not configure the appropriate plugin.
Like most monitoring systems, your effectiveness is determined mostly by 1) your input method and 2) if you have told the system to alert off of all of the correct messages.
