A blockchain is a huge database file of information containing the complete history of every transaction of a coin.
Most cryptocurrencies have their own blockchain, such as Bitcoin and Dash, and some piggyback on the blockchain of another,
such as Gems, which exists as a token on the Ethereum blockchain.
You store physical money in your physical wallet, you store digital money in your digital wallet- software either installed on your computer or on a secure server, which allows you to interact with digital coins and store them at a digital address.
Every digital address has a unique private key that has the power to open its corresponding wallet without the need of a password. So, when you set up your own digital wallet on one of the guides on this site and are given your own private key, you should make a point of storing it safely and never, ever sharing it with anyone.
A physical device devoted to keeping coins safe- by keeping your digital wallet’s private key stored and encrypted. Without access to the hardware wallet, which is itself protected by a password, no-one can access your digital wallet except yourself. I highly recommend getting one yourself if you have any amount of crypto you’d be upset to lose.
Fiat currency is defined as legal tender whose value is backed by the government that issued it. So think dollars, pounds, euros etc. Crypto has no central bank so it’s not a fiat currency.
To some people everything but Bitcoin is an alt coin. To some people everything but Bitcoin and Litecoin is an alt coin. To some people everything but Bitcoin and Ethereum is an alt coin. You see where I’m going with this- what makes a coin an alt coin is based on the opinion of whomever you ask. Though remember Bitcoin did come first, so I’m not sure it will ever be considered an alt coin.
Smart contracts help people exchange money, property, shares- pretty much anything of value- in a transparent, conflict-free way. Both parties can see the code of the contract, and thus the outcome. Smart contracts also avoid the services of a middleman- for instance, when sending money to a friend, banks are the middlemen, taking their cut every step of the way.
ICO (initial coin offering)
An initial coin offering is a means of crowdfunding using cryptocurrency, where a startup company will release a digital currency for investors to purchase (often in the hope it’s going to be the ‘next big thing’).