Solana is a high-performance blockchain platform designed to support the scale, open participation, and performance required to power the next generation of decentralized applications. It is built on a new consensus algorithm called Proof of History (PoH) which allows it to process up to 50,000 transactions per second. Solana also features a unique architecture that allows for low-latency transactions, low transaction fees, and a high degree of decentralization.
The Solana API allows decentralized applications to connect to a Solana node that is part of the Solana blockchain. Developers can interact with on-chain data, send transactions, and deploy contracts by leveraging Alchemy's API endpoints. The API follows a JSON-RPC standard, a lightweight, remote procedure call (RPC) protocol that is commonly used when interacting with blockchain data.
Explained in the Solana API Quickstart Guide.
You can find the list of all the methods Alchemy support for the Solana API on the Solana API Endpoints page.
At the moment, ONLY finalized commitments are supported for WebSocket streams.