NOSQL databases: NoSQL databases are the one which comes in the picture when we no longer work with our traditional databases. "NoSQL" : stand for [NOT ONLY SQL] is an replacement to traditional relational databases in big data world. it is basically schema-free and scalable database, best suitable for solving big data challenges. Properties of NOSQL databases. Schema-free: A SQL database needs to be pre-defined with schema before we can add data to it. A NOSQL database on the other hand allows data insertion dynamically. i.e. we can insert data into NOSQL database without any predefined schema. Scalable : Usually SQL databases scale-up vertically. i.e. when the load is high , the system will be individually upgraded. where as in NOSQL databases it is done horizontally, since these are distributed in nature. Types and Example of NOSQL databases: Key-Value Stores: ex : Redis and Amazon S3 Column-Value Stor...