There are different types of databases. also, There are different ways to classify these types.

You can classify the databases by: 

Database Function:

Analytic Databases:

Also called On Line Analytical Processing (OLAP), it's that databases which are primarily used to keep track of statistics. Usually, they are read-only, meaning that you can only retrieve data, but you can't modify the data in any way.

Operational Databases:

Also called On Line Transaction Processing (OLTP), it's that databases which let you change and manipulate the data. While analytic databases only let you view the data, these databases let you modify the data.

Database Data Model:

Data models are used to describe how the data is stored and retrieved in a database.

Flat-file Database Model:

In this system, data was stored in numerous files. However, the files were not linked, so often, data might be repeated in more than one file. This caused everything to be quite redundant.

Hierarchical Database Model:

The hierarchical database model took steps to get rid of the repetitiveness of the flat-file database model, but although it was somewhat successful, it did not completely succeed. There is still a level of redundant data in hierarchical databases.

Network Database Model:

The network database model was designed to help resolve some of the hierarchical database model's problems. For one thing, it allowed for links between the child databases. This no only reduces the chance of redundant data, but also makes searching for data much easier!

However, the network database model still had its share of problems. For one thing, it was difficult to execute and maintain. Only database experts could successfully use these databases. It was difficult for the general public to use network databases for real-life applications.

Relational Database Model:

the relational database model is extremely popular because it solved many of the
problems displayed in the hierarchical and network database models.

The relational database model is different from the hierarchical and network database models in that there are no "parent" and "child" databases. Rather, all of the databases in the relational database model are equal.

Data can be stored in any number of separate databases. Then, these databases are connected by a "key" field. A key field is a field that is found in all of the databases that are being linked together.

All of the databases can be used to hold different types of data. For example, let's pretend that we have an address book, which is a paper-based database. If we were to use the relational database model, then we would store all of the data in separate databases.

One database could hold a person's address; another could hold the person's phone number, etc. However, all of the databases might have one field that is the same, like, for example, the person's name.

This makes it easy to search for and extract data from the databases. It is also very efficient and easy to use. No wonder why this database model is so popular!

Object-oriented Databases:

You might realize that databases can not only store text and numeric values, but that there are special databases that can also store photos, sounds, videos, and all sorts of graphics. How is this possible? Well, I can tell you one thing, the old hierarchical, network, and relational databases couldn't store all of these types of
data! As a matter of fact, this is where the object-oriented database models come in.

Object-oriented database models let databases store and manipulate not only text, but also sounds, images, and all sorts of media clips! They are extremely useful, but unfortunately, they are large in size and are extremely expensive. Thus, they are only found in large commercial or governmental organizations.

Client/Server Databases

As you probably know, the Internet is one of the most popular usages of a computer. Client/server databases are the databases that you will use for the Internet and for the World Wide Web. The database is left on 24 hours a day, 7 days a week. This is so that users, or clients, can access the web sites or whatever other data is contained in the database at any time they want. This is especially necessary if you want to make the applications available to anybody, anywhere in
the world. There is a special type of interface that lets the clients submit certain data requests from the database. Then, the database will handle and process the requests!