A light Node does not download the complete blockchain. Instead, it downloads the block headers only to validate the authenticity of the transactions. Because of this reason light nodes are easy to maintain and run. Lightweight nodes use a method called Simрlifiеd рауmеnt vеrifiсаtiоn (SPV) to verify transactions.
Lightweight nodes are served by full nodes to connect to the Bitcoin network. They are effectively dependent on the full nodes to function.