So I will answer this in 2 parts. The short version and the long version. The short version is accurate but not many people understand what the words actually mean seeing as something like this has never been created before.

So,
What is Bitcoin?
(short version)

Bitcoin is a ledger that is open for all to see and use and is completely secure, autonomous and decentralized, run on incentives open to all who wish to participate. 
 

What is Bitcoin?
(The longer version)
 

This question can take days, weeks even months to explain thoroughly and in fact the best experts in the world can't even explain fully what Bitcoin is because of how life-changing the technology is. This technology can be more disruptive than the internet was and still is. In 1969 do you think people could fathom Google search or Airbnb or Uber or many of these technologies based upon the internet? The internet still has yet to see it's full potential and as speeds increase and it gains more adoption throughout the world and we will keep seeing amazing things being created, including the creation of Bitcoin.

I bring the internet up because it's relatable to Bitcoin. Bitcoin is currently used as a way to change how we use money in the world but it is so much more than that. With the creation of Bitcoin we can now do alot more things digitally in the world without needing a 3rd party to help without sacrificing security.
Bitcoin allows us to transact with one another anonymously and completely safe.
You can program Bitcoin any way you want as well and it is a completely open source software.
It allows us to have Decentralized companies!

So, lets talk about what that means in the real world. Bitcoin will be able to help send money to anybody in the world instantly with little to no fees, hold a tamper-proof election where people can vote with their cellphones securely, or have existing truly decentralized companies and so much more.
How about politicians? What if somebody decided to put their political campaign on the blockchain? We would know where they get their funds, who is supporting them, how they are spending their money, and eventually vote for them all from your cell phone doing it securely.
If the last election was on the blockchain there would be no question of elections being rigged, everything would be out in the open for everybody to see and we all could vote with our cell phones and have it be completely secure.

Bitcoin is the first practical step towards putting the power back into the peoples hands.
Since the crash happened in 2008 and the government did nothing but bail out everybody who hurt our nation so bad, Bitcoin is the answer to that corruption.
If bitcoin becomes as big as we all hope it becomes it will change the world as we know it and for the first time in mankind's history the power can actually come from the people and we can create a system where corruption can't be hidden away and accountability is reliant on us all.
The first time in history a real money will be able to exist.
 

What is Bitcoin when it comes to money?

An easier way to look at it, it's a form of electronic cash. It could be looked at as internet money but its much more.
It is a decentralized digital currency without a central bank that can be sent from user-to-user on the peer-to-peer network (bitcoin network) without the need for intermediaries.
Bitcoin is the first cryptocurrency to be created and to gain adoption.
Any transactions on the bitcoin network are going to be much cheaper and more secure than any payments made through any 3rd party.
No transaction has ever been reversed.
The fees for transferring money anywhere in the world is cheaper than any bank 99.9% of the time. People have sent millions of dollars from on side of the world to the other and paid pennies for the transaction fee and sometimes less than that.
Most of us reading this are privileged in the sense that we have the ability to create a bank account.
We can have debit and credit cards and we can buy goods and services easily physically and digitally.
Even with our cash, most of us have a currency that does not hyperinflate as bad as most other countries currencies do, so you don't fear holding your countries currency due to it losing value too quickly. For example in 2016, Venezuela entered hyperinflation. The inflation rate reached 274% in 2016, 863% in 2017, 130,060% in 2018 and 9,586% in 2019. Since 2016, the overall inflation rate has increased to 53,798,500%!! in 2018, a cup of coffee cost 450 bolivars in Venezuela. In 2019, a cafe con leche costs 1 million bolivars — or a mere 29 U.S. cents. This happens to every single fiat currency in the world most just inflate over a longer span of time.

So, how did Bitcoin get started?

Nobody knows!

Well, somebody knows but those somebodies are not talking!
It's become one of the best-kept digital secrets of our time and I personally don't care if we ever find out who was the original creator/creators of Bitcoin is, in fact I hope we don't find out. I can't imagine the government and the FED being too kind on the person who disrupted their corrupt industries.

Even though we don't know who originally created Bitcoin  we do have a name: “Satoshi Nakamoto.” This person (or persons) authored a whitepaper titled, Bitcoin: A Peer-to-Peer Electronic Cash System. "Bitcoin.org." was registered on August 18, 2008 and soon after the Bitcoin whitepaper was first introduced on October 31, 2008. It was first posted to a cryptography E-mail list and shared with close friends and like-minded people. On January 3, 2009, the bitcoin network was deployed with the first open-source application using a software client. This is also when the first Bitcoin transaction took place, there was 50 of them sent. Satoshi Nakamoto stayed active in the Crypto community until April 2011. Since then, nobody has heard from Satoshi and the rest of the development of Bitcoin was left to anybody who wished to help develop.

Was there anything before Bitcoin?

YES!

There were many technologies and digital protocols used in the creation of bitcoin and a number of individuals and creators behind those inventions before Bitcoin was birthed!

Here are specific technology inventions that Satoshi Nakamoto uses, mentions, and gives credit in his whitepaper:

1. a digital cash technology and protocol called ecash by David Chaum and Stefan Brands

2. a “proof of work” system called hashcash by Adam Back for spam monitoring and control, which was eventually built upon by Hal Finney, who created a reusable proof-of-work protocol

3. a distributed scarcity system built upon “b-money” created by Wei Dai

4. a technology called “bitgold” by Nick Szabo that proposed a mechanism for market inflation control
    

All of these people have denied being Satoshi Nakamoto.
 

Nobody knows who Satoshi Nakamoto is even tho many have claimed to be Satoshi. The most recognizable name is Craig Wright but we will talk about him later.
 

Essentially what you need to know is that Bitcoin was created to be the next generation of money.

We went from our very first version of money 30,000 years ago scratching tally marks on rocks to bartering, trading goods and services to Gold to paper money to credit cards and now bitcoin is the next wave!

Next lesson we will talk about how bitcoin works a bit more under the hood. For now, check out these links to tide your curiosity until the next lesson.

1. Bitcoin White Paper
2. Advances in Cryptology Proceedings (ecash) by David Chaum
3. Bit gold by Nick Szabo
4. Reusable proof of work by Hal Finney