A database is a collection of data in an arranged structure. database is stored in a way to readable for devices and computers. for example, when you sign up in a website, your username and password is stored in a database and every time you try to login, your account information is verified by that database. databases record all data needed for a software to make sure it works properly.
blockchain is a collection of databases and every database in a blockchain is called a block.
in blockchain databases, all devices are responsible for storing, processing and safeguarding the incoming data. all nodes work together to make sure the achieved result is correct and therefore the network is safe.

Decentralized control
Blockchain databases can’t be accessed or controlled by a person or an organization. because different computers around the world are responsible for creating and managing the network. no one has the ability to tamper or hack all of these devices. in centralized databases, a person or an organization is responsible for the database and can change it or remove a part of data.
for example, Twitter is a centralized social media app responsible for the security of our data. but it has been hacked many times. also, many tweets have been removed by the request of governments. using blockchain technology, only the owner of an account can change or delete a post. even the owners of that company won’t be able to do this.
many banks and website has been the target of different hackers in the past years which has resulted in the loss of assets. the reason is simple, hacker only have to gain access to a few servers and then they get what they want. but in blockchain, hackers face millions of computers and have to hack more than %51 of them to be able to control the network and change the data which is impossible.
most databases store data for a limited period of time and the data can be lost if a malfunction happens in the server.
Blockchain databases have the ability to store unlimited data without the possibility of changing it. this will revolutionize the data storing techniques. for example, no one can tamper or remove a criminal record from a blockchain database and all data recorded from day one will remain in the network forever.

Speed
While blockchain databases are much more efficient than regular databases, they are slightly slower than others like PayPal or VISA. more processing power doesn’t always deliver a faster system. the nature of blockchain is to let all computers vote on the credibility of a transaction or a report and more computers mean more voter and therefore longer time. although the longest time it take for the worst case senario to be confirmed is than one hour which means that this delay will not be able to stop this amazing technology from thriving.

Confidentiality
Bitcoin is a decentralized database which means that everyone can introduce a new block to the network or read a block from blockchain using a license. the confidentiality of transactions using encryption keys is one of the most important advantages of blockchain.