Basically, Splunk is mainly used for monitoring and searching through big data. It indexes and correlates information in a container that makes it searchable, and makes it possible to generate alerts, reports, and visualizations. The reason for being popular it is scalable and available on a variety of platforms and can be quickly implemented on any software. If one server is insufficient, another can be quickly added, and data is spread evenly between the two servers.
If you are planning to boost your knowledge in this technology then I recommend you to take up this Intellipaat Splunk-Certification-Training.
Before that do check out this video on how Intellipaat helped Uday Agarwal in getting a salary hike -