What is Nxt?Nxt is considered a second-generation crypto currency. With all the altcoins coming out that only change things such as hashing mechanism, time between blocks, starting difficulty, and so on, Nxt brings much much more to the table and was designed this way for a number of reasons:
It is not an "alt coin" like coins such as litecoin, peercoin, and others who have their code based on Bitcoin's source code. It is brand new from scratch with its own code.
It provides built in support for planned extra features such as a decentralized peer-peer exchange, colored coins, messaging/chat, decentralized DNS, and options for instant transactions.
It is a 100% proof of stake (PoS) versus the proof of work (PoW) mechanism the vast majority of other coins are based on. This effectively removes a large security risk inherent in most other coins, as the issue of a 51% attack or other vulnerabilities inherent to PoW coins is gone. The biggest plus here is how "green" this protocol is in terms of power consumption, since PoS doesn’t require massive amounts of hashing power
It was announced weeks in advance, unlike mere hours like most coins. The 71 stakeholders are responsible for distributing the 1 billion Nxt coins that were ejected from the genesis block via an injection of bitcoin (donated by them, 21 BTC total) into the genesis block. This is a requirement for this PoS system to work and this distribution is now in progress.
Why are all Nxt coins pre-mined?The term "pre-mined" is really a misnomer. Nxt coins are not mined at all. The original stakeholders in Nxt contributed Bitcoin in order to seed the creation of the 1 billion coins represented in the genesis block, and these coins were distributed among the original stakeholders. Even the creator of Nxt (BCNxt ) made an investment.
The coins were not generated from nothing!The creation of the genesis block was fully public:
https://bitcointalksearch.org/topic/m.3652710If there are no new Nxt to be mined, how do you validate the blockchain and secure the network?Nxt is a pure Proof-of-Stake (PoS) currency. Users validate the blockchain and secure the network by running a light weight client on any computing device (even one that used to run Windows XP). For doing this users are rewarded with Nxt coin that is collected from transaction fees.
http://nxtcoin.wikia.com/wiki/The_Nxt_Wiki