“The blockchain is an incorruptible digital ledger of economic transactions that can be programmed to record not just financial transactions but virtually everything of value.”
Don & alex tapscott
Simply- a blockchain is a huge file of information containing the complete history of every transaction of a coin ever made.
Consider a special google spreadsheet which is shared by every computer in the world and is connected to the internet. Every time a transaction happens, it gets recorded onto a row of this spreadsheet.
Anyone with a mobile device or computer can connect via the internet and can access the spreadsheet. Anyone can view and add a transaction to this spreadsheet, but the spreadsheet doesn’t allow anyone to edit the information which is already there.
This is basically a 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 you are given your own private key, you should make a point of storing it safely and never, ever sharing it with anyone.
To some people everything but Bitcoin is an alt coin and I feel the same as Bitcoin came first, before any other coins. what makes a coin an alt coin is based on the opinion of whomever you ask.