After looking at the building blocks, structure, and core parts of the blockchain, we are now going to learn about the various types of blockchain implementations available, and we will also look at their features and benefits. As we already know, the Bitcoin blockchain became popular for its immutability, security, robustness, and transparency. The industry was in need of the Bitcoin blockchain architecture, but there were challenges that came up. 

The challenges faced by the industry are as follows:

• How will it cater to an enterprise's specific needs: We know that the Bitcoin blockchain is open source, which is open to all kinds of solutions. If the IT industry or various enterprises wanted to use this blockchain architecture, they would not be able to use it as their needs are different.
• How can we use other currencies with blockchain: Enterprises that were willing to use the blockchain architecture due to its immutability, security, and transparency wanted to track their own assets, which wasn't possible in Bitcoin blockchain as it was using Bitcoin and other Altcoins as currency.
• How will it allow us to define specific roles and permissions on the blockchain: Different enterprises have their own roles, privileges, and permissions that have to be captured and executed on the blockchain nodes. In the case of the Bitcoin blockchain, we know that each and every node plays the same role across the globe. 

So, these challenges triggered the need for specific changes to blockchain for industries, enterprises, and IT companies, in order to use blockchain for their own purposes, which in turn gave birth to different blockchain versions or variants.