https://blog.ethereum.org/2014/05/06/daos-dacs-das-and-more-an-incomplete-terminology-guide/
Blockchain
A blockchain is a distributed computing architecture where every network node executes and records the same transactions, which are grouped into blocks. Only one block can be added at a time, and every block contains a mathematical proof that verifies that it follows in sequence from the previous block. In this way, the blockchain’s “distributed database” is kept in consensus across the whole network.
Security
Individual user interactions with the ledger (transactions) are secured by strong cryptography. Nodes that maintain and verify the network are incentivized by mathematically enforced economic incentives coded into the protocol.
Decentralization
On traditional server architectures, every application has to set up its own servers that run their own code in isolated silos, making sharing of data hard. If a single app is compromised or goes offline, many users and other apps are affected. On a blockchain, anyone can set up a node that replicates the necessary data for all nodes to reach an agreement and be compensated by users and app developers. This allows user data to remain private and apps to be decentralized like the Internet was supposed to work.
Ethereum Virtual Machine
The Ethereum Virtual Machine (a.k.a. EVM) is the runtime environment for smart contracts in Ethereum. It is actually completely isolated, which means that code running inside the EVM has no access to network, filesystem, or other processes. This EVM makes Ethereum a programmable blockchain. It allows users to create their own operations of any complexity they wish. In this way, it serves as a platform for many different types of decentralized blockchain applications, including but not limited to cryptocurrencies.
Every Ethereum node runs the EVM in order to maintain consensus across the blockchain. Decentralized consensus gives Ethereum extreme levels of fault tolerance, ensures zero downtime, and makes data stored on the blockchain forever unchangeable and censorship-resistant.
Wallet
To manage your Ether and Tokens comfortably, you need a special software application called Wallet. The Mist Wallet is an open source application developed by the Ethereum Foundation.
Smart contract
A contract is a collection of code (its functions) and data (its state) that resides at a specific address on the Ethereum blockchain. Contract accounts are able to pass messages between themselves as well as doing practically Turing complete computation.
Solidity, Serpent, LLL
Contracts live on the blockchain in a Ethereum-specific binary format called Ethereum Virtual Machine (EVM) bytecode. Contracts are typically written in some high level language such as Solidity and then compiled into bytecode to be uploaded on the blockchain. There are some high-level languages and compilers to generate this bytecode:
- Solidity has many resemblance with Javascript, but it is static typed and there are some special constructs.
- Serpent is a deviation from python
- LLL is a low-level, Lisp-like Language
Ethereum client
Ethereum network
Smart contracts
Nick Szabo 1994 article
Security
http://www.dejavusecurity.com/blog/2015/7/23/deja-vu-security-assists-in-ethereum-release