Types of NoSQL databases :

NoSQL databases come in several distinct types, each with its own data model and strengths:  

1. Document Databases

• Data Model: Stores data in flexible documents, often in JSON format.  
• Key Features:
• Easy to represent complex, hierarchical data structures.
• Schema-less or flexible schema, allowing for evolving data structures.  
• Good for applications with frequent data updates and unstructured data.  
• Examples: MongoDB, Couchbase, DocumentDB  

2. Key-Value Stores

• Data Model: Stores data as simple key-value pairs.  
• Key Features:
• Extremely fast for simple read and write operations.  
• Often used for caching, session management, and storing small pieces of data.  
• Examples: Redis, Memcached, Amazon DynamoDB  

3. Column-Family Stores (Wide-Column Stores)  

• Data Model: Organizes data into columns, allowing for efficient storage and retrieval of specific columns.  
• Key Features:
• Excellent for storing large amounts of time-series data or data with sparse attributes.  
• Highly scalable and distributed.  
• Examples: Cassandra, HBase  

4. Graph Databases

• Data Model: Represents data as nodes and relationships between them.  
• Key Features:
• Ideal for storing and querying data with complex relationships, such as social networks, recommendation systems, and knowledge graphs.  
• Examples: Neo4j, Amazon Neptune  

5. Multi-model Databases

• Data Model: Support multiple data models within a single database, such as document, key-value, and graph.  
• Key Features:
• Offer flexibility and can adapt to different data requirements within a single application.  
• Examples: Azure Cosmos DB, Amazon DocumentDB  

This overview provides a general understanding of the different types of NoSQL databases. The choice of which type to use depends on the specific requirements of your application, such as data structure, scalability needs, and query patterns.