Solana is a popular alternative to Ethereum (ETH). Solana is a public blockchain platform. It achieves consensus using proof of stake and proof of history. Its internal cryptocurrency is SOL. Bloomberg considers Solana to be "a potential long-term rival for Ethereum" and like Ethereum, Solana can interact with smart contracts.
Smart contracts are tiny pieces of code that allow blockchain platforms to run decentralized applications (dApps) and other programs. The trouble with Ethereum's network is that it is heavily congested and transactions have become expensive.