Acronym for Ethereum Request for Comments (ERC), this is a standard for the development of the Ethereum blockchain. Basically, the range of ERC's comprise the recommended development standards across the Ethereum network and, in line with a decentralized approach, the adopted standards are those most accepted by the community. The currently adopted standard is ERC 20, which comprises almost all issued ERC tokens.
This standard would allow for the acceptance of multiple types of Ethereum tokens in a single transaction. This would include fungible, non-fungible and alternate configurations that could be spent in one transaction.
ERC 20 Token Standard
The flagship standard of Ethereum development, ERC 20 accounts for almost all issued tokens. Because it is the most widely adopted standard, the Ethereum community has a stable, non-conflicting set of applications and smart contracts across the network. It is anticipated that the community will continue with the ERC 20 standard for the foreseeable future. Other token standards exist such as ERC 20, ERC 223, ERC 621, ERC 721 and others, but these have not reached widespread acceptance over ERC 20.
ERC 223 Token Standard
In order to help prevent or recover lost tokens, the ERC 223 standard was created. This standard solved the problem of tokens sent to a contract not designed to work with sent tokens, so the tokens are lost. This uncommon event has diminished in importance, especially with ENS (Ethereum Name Service) which has reduced the number of times this happens even further. For that reason, this standard was not widely supported. It is worth noting that ERC 223 uses less gas to complete the transaction than the ERC 20 standard.
This standard allows for the increase and decrease of token supply. Where ERC 20 allows for static supply amounts, ERC 621 allows for change in token supply. As an extension of ERC 20, ERC 621 is cross-compatible.
ERC 721 Token Standard
Most coins are identical. Non fungible means that coins, while they spend in the same fashion, may represent a different underlying asset. Real estate where a coin, equal in value, represents a specific portion of that real estate, is called non-fungible. Crypto Kitties is another example. The token spends the same, but the Kitty is different. ERC 721 solves that problem.
As a derivative of the ERC 20 standard, ERC 827 is cross compatible with ERC 20. This extension allows for the transfer or tokens and also allows token holders to approve spending of tokens by third parties. This opens a entirely new realm of transaction types for token holders.
Whenever a transaction occurs on the Ethereum network, a transaction fee also known as gas is used to facilitate the transaction. Ether is the gasoline that makes the Ethereum Blockchain network and entire Ethereum ecosystem run. It is the incentive for network participants to facilitate transactions.
Think of Ethereum as another coin. The blockchain application, operates on the same principles as Bitcoin but with significant modifications that allow it to utilize smart contracts and carry a heavier data payload than its bigger counterpart. These smart contracts are the result of users creating their own decentralized "chains" as it were to create functionality and data within the Ethereum blockchain.
A Turing complete, 256 bit Virtual Machine, the Ethereum Virtual Machine or EVM allows anyone to execute arbitrary EVM byte code. It is part of the protocol for ETH and is critical to consensus in the Ethereum (ETH) ecosystem. Every Ethereum node runs on the EVM and works to maintain consensus through the entire Ethereum network.
Almost identical to a stock exchange as we know it, the primary function of the exchange in the crypto space is to exchange one cryptocurrency for another. All crypto exchanges accept certain forms of crypto as deposits and will payout in crypto as well. There are two primary differentiators when researching exchanges in the blockchain space. First is liquidity, which often dictates ability to payout quickly and always impacts volatility. The second differentiator to look for is whether the exchange also accepts fiat for deposits and can payout fiat in withdrawals as well. The exchange makes their money via spreads and transaction fees. The location of the exchange and government oversight may regulate exchange policies.