vscode-languageserver-types defines the core data structures and interface definitions used in the Language Server Protocol (LSP). Crucial for building language server extensions for VS Code and other LSP-compatible editors, it provides TypeScript definitions for diagnostics, completion items, document symbols, and more. This package facilitates seamless communication between a language server and an editor, enabling rich code editing features like syntax highlighting, code completion, and error checking by defining a common type system.