Electrum is a wallet of Bitcoin available for PC, Linux and Android which was created by Thomas Voegtlin a German computer scientist. He estimates it about 10 of bitcoin transactions to send using electrum. It is used for creating secure cold storage offline. Offline computer can be used for generating master private and public keys. Its master public key will be scanned in the online computer. Online computer helps to receive payments and offline secures transactions.
A unique feature of Electrum is sending from ability. The Electrum wallet Bitcoin Diamond HD contain various inputs. While the time of spending, it just feels silly for spending 1 Bitcoin input if 0.01 Bitcoin only must be spent. Electrum send from will allow the owner wallet to select input that is used in transaction. This selected input can be frozen and will not be included in any outgoing transaction automatically.
Electrum for Bitcoin Diamond syncs fast and is lightweight but the feature is packed with Bitcoin wallet. It supports multi-signature wallet and two-factor authentication. This wallet is an open source with source code available.
This client does not require to download its blockchain that request information from the server. No need of delay so always it is up-to-date.
Private keys get encrypted and will not leave the computer. The wallet is recovered from some secret phrase. Also, you can keep the private keys offline and then go online to see wallet.
The private keys will not get shared with its server. As you cannot trust a sever with money, this encrypted private keys will never leave the computer. Server of electrum Bitcoin Diamond will not store the user account. Therefore, you are not getting tied with any particular server and this server does not need you to know.