Databases are a type of computer program that stores data and then lets you access it later. They are essential to a lot of computer applications, and are used in many ways throughout your everyday life.

A database is a logically organized collection of information that can be accessed for use by a computer program. It solves two important problems that computers face: how to store information so that you can find it later, and how to keep track of it when it changes.

Different types of databases exist, each based on the type of information they store and how it is arranged. These include relational, in-memory, object, graph, cloud, time series and distributed databases.

The underlying structure of databases is called the data model. The most common type of data model is the relational database model, which organizes information into tables.

There are also many other types of databases, ranging from full text to directory to scientific and chemical databases. A few of the more popular ones are Amazon DynamoDB, Redis and HBase. Generally, these systems are scalable and can handle humongous amounts of data. They are often deployed for e-commerce sites, social networks and telecommunications companies. They are typically managed by a DBMS (database management system). Some of these systems can be implemented as open source software or proprietary programs. They are also commonly deployed in the cloud, where they provide on-demand scalability and high availability. They are particularly useful in business applications and customer relationship management systems.