Non-upgradeable scaling means that the existing technical system of Bitcoin is not changed, and only the existing characteristics of Bitcoin are used to achieve a specific type of expansion.

Representative technologies include RGB and BitcoinScript. RGB is a scalable and encrypted smart contract system that can run directly on the Lightning Network, but all the data it generates exists outside the Bitcoin transaction (off-chain), which means that the security of the entire ledger cannot rely on the security of the Bitcoin mainnet.

Ordinal is implemented using BitcoinScript to add additional data and assign a unique serial number to each of the smallest units of Bitcoin, Satoshis (Sats). This method can only make minor improvements to Bitcoin's scalability. At present, there is a wave of hype around Bitcoin NFTs and BRC-20 tokens in the market, but the sustainability of their value remains to be seen.

Excluding the functions assigned to Sats by third parties, from the perspective of the Bitcoin mainnet, the data attached to various Scripts are meaningless garbled codes, resulting in a waste of Bitcoin block space and transaction congestion, which has also caused strong dissatisfaction among some members of the Bitcoin community.

In general, the non-upgraded expansion technology solution is decentralized and does not require the overall consensus of the Bitcoin community in terms of implementation difficulty, but at the same time, RGB fails to rely on the consensus security of the Bitcoin mainnet, and the scalability of Bitcoin transactions through scripts is very limited.

The second method is the sidechain, which creates a separate chain and links it to the Bitcoin mainnet through a specific cross-chain technology.

This was once a popular and relatively easy-to-implement Bitcoin expansion solution, mainly because sidechain projects can issue their own tokens, which can attract community and market interest as their value increases. However, the main participants in this solution have some problems in expanding Bitcoin.

Projects such as Liquid (BlockStream), Stacks, and Rootstock map BTC to sidechains through a two-way cross-chain bridge, which is their common feature, but there are also subtle differences.

Liquid is more like a Bitcoin alliance chain composed of large institutions, and the BTC mapping and conversion between the sidechain and the mainnet requires a multi-signature agreement from these institutions.

Stacks is a Bitcoin sidechain technology that issues new tokens. Its PoX protocol is a protocol that allows miners to stake BTC by staking STX. However, how the protocol achieves decentralized distribution remains to be studied.

Rootstock uses merged mining sidechain technology, and the cross-chain transfer of BTC is controlled by multiple signatures of multiple institutions (BTC→rBTC).

However, sidechain nodes are not accessible to everyone, and the ledger consensus relies on the management of certain centralized institutions, resulting in a low degree of decentralization. This may be the main reason why the sidechain scaling solution has not been widely adopted after many attempts.

Upgrade-based scaling refers to the need to upgrade the technical architecture or technical system of the Bitcoin network. A representative example is BIP-300/301 proposed by the LayerTwoLabs team. Its scaling concept is called Drivechain, which essentially uses Rollup to scale.

At present, LayerTwoLabs' approach is to directly hard fork a PoW main chain with BIP-300/301. When the Bitcoin community reaches a consensus and recognizes this main chain, the Bitcoin mainnet will be upgraded to BIP300/301.

Overall, LayerTwoLabs' solution can ensure the decentralization of Bitcoin and solve the expansion problem. However, its expansion upgrade requires the consensus of the Bitcoin community, and under the current overall atmosphere of the community, it is extremely difficult to upgrade the Bitcoin mainnet.

Bitcoin's two-way transfer is a common method in cross-chain and sidechain scenarios. Bitcoin's one-way transfer expansion solution was proposed by the Hacash community and the Hacash.com team. The principle is to irreversibly transfer Bitcoin to a new chain that is more decentralized and more technologically mature in theory, and then use a multi-layer approach for scalability.

The first layer of Hacash can realize the one-way transfer of Bitcoin, transferring BTC on the Bitcoin chain to the Hacash chain. During the transfer process, the user's private key remains unchanged, and the same private key can be used directly to use Bitcoin on the Hacash chain, and the control of BTC is not transferred to any other entity.

Based on the Hacash chain, there are Layer1 and Layer2 payment networks, and the Hacash.com team has also proposed a Layer3 multi-chain scalability infrastructure. Bitcoin can be used for instant payments on Layer2 and for application expansion on Layer3. The essence of Layer2 is to use state channels for instant payments, and the essence of Layer3 is to use multi-rollup and multi-rollup customizable scalability methods.

Overall, the Hacash chain that accepts BTC one-way transfers still uses a pure PoW consensus mechanism, and anyone can run a full node. Its degree of decentralization and security are not weaker than the original Bitcoin chain.

On top of this, Layers 2 and 3 solve the scalability problem. Anyone can choose to transfer their BTC to the Hacash mainnet, and it is up to each Bitcoin holder to decide whether they need scalability. The implementation difficulty is lower than other solutions, and the selectivity is strong.

Non-upgradeable scaling means that the existing technical system of Bitcoin is not changed, and only the existing characteristics of Bitcoin are used to achieve a specific type of expansion.

Representative technologies include RGB and BitcoinScript. RGB is a scalable and encrypted smart contract system that can run directly on the Lightning Network, but all the data it generates exists outside the Bitcoin transaction (off-chain), which means that the security of the entire ledger cannot rely on the security of the Bitcoin mainnet.

Ordinal is implemented using BitcoinScript to add additional data and assign a unique serial number to each of the smallest units of Bitcoin, Satoshis (Sats). This method can only make minor improvements to Bitcoin's scalability. At present, there is a wave of hype around Bitcoin NFTs and BRC-20 tokens in the market, but the sustainability of their value remains to be seen.

Excluding the functions assigned to Sats by third parties, from the perspective of the Bitcoin mainnet, the data attached to various Scripts are meaningless garbled codes, resulting in a waste of Bitcoin block space and transaction congestion, which has also caused strong dissatisfaction among some members of the Bitcoin community.

In general, the non-upgraded expansion technology solution is decentralized and does not require the overall consensus of the Bitcoin community in terms of implementation difficulty, but at the same time, RGB fails to rely on the consensus security of the Bitcoin mainnet, and the scalability of Bitcoin transactions through scripts is very limited.

The second method is the sidechain, which creates a separate chain and links it to the Bitcoin mainnet through a specific cross-chain technology.

This was once a popular and relatively easy-to-implement Bitcoin expansion solution, mainly because sidechain projects can issue their own tokens, which can attract community and market interest as their value increases. However, the main participants in this solution have some problems in expanding Bitcoin.

Projects such as Liquid (BlockStream), Stacks, and Rootstock map BTC to sidechains through a two-way cross-chain bridge, which is their common feature, but there are also subtle differences.

Liquid is more like a Bitcoin alliance chain composed of large institutions, and the BTC mapping and conversion between the sidechain and the mainnet requires a multi-signature agreement from these institutions.

Stacks is a Bitcoin sidechain technology that issues new tokens. Its PoX protocol is a protocol that allows miners to stake BTC by staking STX. However, how the protocol achieves decentralized distribution remains to be studied.

Rootstock uses merged mining sidechain technology, and the cross-chain transfer of BTC is controlled by multiple signatures of multiple institutions (BTC→rBTC).

However, sidechain nodes are not accessible to everyone, and the ledger consensus relies on the management of certain centralized institutions, resulting in a low degree of decentralization. This may be the main reason why the sidechain scaling solution has not been widely adopted after many attempts.

Upgrade-based scaling refers to the need to upgrade the technical architecture or technical system of the Bitcoin network. A representative example is BIP-300/301 proposed by the LayerTwoLabs team. Its scaling concept is called Drivechain, which essentially uses Rollup to scale.

At present, LayerTwoLabs' approach is to directly hard fork a PoW main chain with BIP-300/301. When the Bitcoin community reaches a consensus and recognizes this main chain, the Bitcoin mainnet will be upgraded to BIP300/301.

Overall, LayerTwoLabs' solution can ensure the decentralization of Bitcoin and solve the expansion problem. However, its expansion upgrade requires the consensus of the Bitcoin community, and under the current overall atmosphere of the community, it is extremely difficult to upgrade the Bitcoin mainnet.

Bitcoin's two-way transfer is a common method in cross-chain and sidechain scenarios. Bitcoin's one-way transfer expansion solution was proposed by the Hacash community and the Hacash.com team. The principle is to irreversibly transfer Bitcoin to a new chain that is more decentralized and more technologically mature in theory, and then use a multi-layer approach for scalability.

The first layer of Hacash can realize the one-way transfer of Bitcoin, transferring BTC on the Bitcoin chain to the Hacash chain. During the transfer process, the user's private key remains unchanged, and the same private key can be used directly to use Bitcoin on the Hacash chain, and the control of BTC is not transferred to any other entity.

Based on the Hacash chain, there are Layer1 and Layer2 payment networks, and the Hacash.com team has also proposed a Layer3 multi-chain scalability infrastructure. Bitcoin can be used for instant payments on Layer2 and for application expansion on Layer3. The essence of Layer2 is to use state channels for instant payments, and the essence of Layer3 is to use multi-rollup and multi-rollup customizable scalability methods.

Overall, the Hacash chain that accepts BTC one-way transfers still uses a pure PoW consensus mechanism, and anyone can run a full node. Its degree of decentralization and security are not weaker than the original Bitcoin chain.

On top of this, Layers 2 and 3 solve the scalability problem. Anyone can choose to transfer their BTC to the Hacash mainnet, and it is up to each Bitcoin holder to decide whether they need scalability. The implementation difficulty is lower than other solutions, and the selectivity is strong.