Bitcoin

To cut through some of the confusion surrounding bitcoin, we need to separate it into two components. On one hand, you have bitcoin-the-token, a snippet of code that represents ownership of a digital concept. On the other hand, you have bitcoin-the-protocol, a distributed network that maintains a ledger of balances of bitcoin-the-token. Both are referred to as "bitcoin."

Blockchain is the most widely used and well-known system that enables payments to be sent between users without passing through a central authority, such as a bank or payment gateway. Bitcoins aren't printed, like USD dollars or Euros. Instead, they're produced by computers all around the world, using software.

It was the first example of what we today call cryptocurrencies, an asset class that shares some characteristics of traditional currencies, with verification based on cryptography.

-Coindesk

Who created it?

An anonymous software developer that goes by the name of Satoshi Nakamoto created bitcoin in 2008, as an electronic payment system based on mathematical proof. The idea was to produce a means of exchange, independent of any central authority, that could be transferred electronically in a secure, verifiable and immutable way..

To this day, no one knows who Satoshi Nakamoto really is.

-Coindesk

Dogecoin

code: DOGE, symbol: Ð and D) is a cryptocurrency featuring a likeness of the Shiba Inu dog from the "Doge" Internet meme as its logo. Introduced as a "joke currency" on 6 December 2013, Dogecoin quickly developed its own online community and reached a capitalization of US$60 million in January 2014.

Compared with other cryptocurrencies, Dogecoin had a fast initial coin production schedule: 100 billion coins were in circulation by mid-2015, with an additional 5.256 billion coins every year thereafter. As of 30 June 2015, the 100 billionth Dogecoin had been mined. While there are few mainstream commercial applications, the currency has gained traction as an Internet tipping system, in which social media users grant Dogecoin tips to other users for providing interesting or noteworthy content. Dogecoin is referred to as an altcoin.

-Wikipedia