Types of Databases

A database is a collection of data that is organized in a certain way to facilitate easy access and retrieval of information. There are several types of databases, including:

1. Hierarchical Database
A hierarchical database is a type of database that stores data in a tree-like structure where each record has one parent record and many children records. This type of database is best suited for applications that have a one-to-many relationship between data entities.

2. Network Database
A network database is a type of database that is similar to a hierarchical database, but with a more complex structure. In a network database, each record can have multiple parent and child records, making it more flexible than a hierarchical database.

3. Distributed Database
A distributed database is a type of database where data is stored across multiple computers or servers. This type of database is useful in situations where data needs to be accessed from different locations and needs to be updated in real-time.

4. Decentralized Database
A decentralized database is a type of database where there is no central authority controlling the data. Instead, each user or node has a copy of the entire database, and updates are made by consensus among the nodes.

Answer Explanation

Based on the above types of databases, the correct answer is option D, Decentralized Database, as it is not a recognized type of database.