ICO is the abbreviation of Initial Coin Offering. It means that someone offers
investors some units of a new cryptocurrency or crypto-token in exchange against
cryptocurrencies like Bitcoin or Ethereum. Since 2013 ICOs are often used to
fund the development of new cryptocurrencies. The pre-created token can be
easily sold and traded on all cryptocurrency exchanges if there is demand for
them.
With the success of Ethereum ICO are more and more used to fund the development
of a crypto project by releasing token which is somehow integrated into the
project. With this turn, ICO has become a tool that could revolutionize not just
currency but the whole financial system. ICO token could become the securities
and shares of tomorrow.
Ethereum is a decentralized platform that runs smart contracts: applications
that run exactly as programmed without any possibility of downtime, censorship,
fraud or third-party interference.
These apps run on a custom built blockchain, an enormously powerful shared
global infrastructure that can move value around and represent the ownership of
property.
This enables developers to create markets, store registries of debts or
promises, move funds in accordance with instructions given long in the past
(like a will or a futures contract) and many other things that have not been
invented yet, all without a middleman or counterparty risk.
Ethereum official website
https://www.ethereum.org
A Block Explorer is basically a search engine that allows users to easily
lookup, confirm and validate transactions that have taken place on the Ethereum
Blockchain.
Etherscan
https://etherscan.io
A DAO (Decentralized Autonomous Organization) can be seen as the most complex
form of a smart contract, where the bylaws of the decentralized organization are
embedded into the code of the smart contract, using complex token governance
rules.
How DAOs work
Decentralized Autonomous Organisations (DAOs) run through rules encoded as
computer programs called smart contracts. It is an entity that lives on the
internet and exists autonomously, but also heavily relies on hiring individuals
to perform certain tasks that the automaton itself cannot do.
DApp is an abbreviated form for decentralized application.
A DApp has its backend code running on a decentralized peer-to-peer network.
Contrast this with an app where the backend code is running on centralized
servers.
A DApp can have frontend code and user interfaces written in any language (just
like an app) that can make calls to its backend. Furthermore, its frontend can
be hosted on decentralized storage such as Swarm or IPFS.
For an application to be considered a Dapp (pronounced Dee-app, similar to
Email) it must meet the following criteria:
The Ethereum token standard (ERC20) defines a common list of rules that an
Ethereum token has to implement. Giving developers the ability to program how
new tokens will function within the Ethereum ecosystem. This token protocol
became popular with crowdfunding companies via initial coin offering
(ICO).
Technical specification
https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
"Gas" is the name for a special unit used in Ethereum. It measures how much
"work" an action or set of actions takes to perform.
Every operation that can be performed by a transaction or contract on the
Ethereum platform costs a certain number of gas, with operations that require
more computational resources costing more gas than operations that require few
computational resources.
The reason gas is important is that it helps to ensure an appropriate fee is
being paid by transactions submitted to the network. By requiring that a
transaction pay for each operation it performs (or causes a contract to
perform), we ensure that network doesn't become bogged down with performing a
lot of intensive work that isn't valuable to anyone.
Good explanation of Gas
https://ethereum.stackexchange.com/questions/3/what-is-meant-by-the-term-gas
How to estimate Gas price
https://ethgasstation.info