♦WHAT IS ELASTICSEARCH 
►ElasticSearch is open source, distributed NoSQL database which allows real time searching & analysing of big data.
►ElasticSearch allows us very powerful searches over huge amount of data and also considered as Big Player in Big data Analytics.
►It can store & process all types of data including textual, numerical, structured, semistructured & unstructured.
►ElasticSearch is built based on Apache Lucene library.
►ElasticSearch was first released in 2010 by ElasticSearch N.V.(now known as Elastic).
►Features :-
►NoSQL Database
►Scalable & Distributed
►Fault Tolerant
►Searchings are very fast
►Schema Free
►Multilingual
♦WHAT IS ELASTIC STACK (ELK)
►E => ElasticSearch, L => LogStash, K => Kibana.
►It is nothing but a Set of open source tools like ElasticSearch, Kibana, LogStash, Beats etc.
►ElasticSearch is the central as well as storage component in Elastic Stack.
►LogStash is used for Data Ingestion to ElasticSearch.
►Kibana provides Web UI for Analysis & Visualization.
