Dash Electrum is a light wallet which uses powerful external servers to index the blockchain, while still securing the keys on your personal computer. Transactions are verified on the Dash blockchain using a technique called Secure Payment Verification (SPV), which only requires the block headers and not the full block. This means that wallet startup is almost instant, while still keeping your funds secure and mobile. Dash Electrum also supports advanced InstantSend, CoinJoin and masternode features.
Dash Electrum is a fork of the Electrum wallet for Bitcoin. While this documentation focuses on using Dash Electrum, full documentation of all Bitcoin Electrum features (mostly identical in Dash Electrum) is available at the official documentation site.