Layer-1 is the base blockchain technology that supports transactions and refers to underlying technology such as Bitcoin and Ethereum. The original blockchain networks, Layer-1 blockchains, could experience challenges related to scalability due to technological limitations.
Layer-1 blockchain networks serve as the infrastructure where on-chain transactions are conducted. However, in addition to scalability, the Layer-1 networks could also experience limited throughput, offering lower transaction processing speeds. They also have higher transaction costs than the scaling solutions designed to operate on top of them.
These challenges led to the development of Layer-2 networks built on top of Layer-1 networks, offering improved scalability and efficiency. Such technologies, however, continue to rely on the underlying Layer-1 blockchain to provide security and consensus.