Public blockchain (permissionless)

The blockchain concept has been widely used and adapted due to its transparency and how every node participates in contributing to the growth of the blockchain. The early blockchain model, the product of Bitcoin, is completely open and permissionless and is popularly known as a public blockchain. Public blockchains are popular due to the impartial way in which the nodes are treated.

Public blockchains work seamlessly in trustless networks due to the immutable nature of the records. Bitcoin, Ethereum, and several other projects that have inherited PoW-like consensus algorithms ensure that recorded transactions are non-editable.

Public blockchains are ideal for cryptocurrency projects where recorded transactions should not be modified. However, public blockchains often face scalability issues at some point if the necessary changes aren't implemented. One of the most visible issues of Bitcoin is its mining approach (PoW), which is very expensive in terms of the electricity required for miners to solve the puzzle. The average time for block creation is 10 minutes. Therefore, the difficulty level of mining has been adjusted to maintain this time. This has resulted in a very expensive PoW environment due to competition among miners. We'll not be able to predict the future of Bitcoin or any other public blockchain due to these complex attributes, and only the natural evolution of the technology can decide its fate.

Due to these pros and cons, the permissionless or public blockchain is well suited for transparent applications, where the blockchain should inherently secure the system since the network is trustless.