In the beginning, there was only Bitcoin, created by Satoshi Nakamoto.

But due to the open source nature of Bitcoin, this didn't last.

"Source code" is the node that programmers can manipulate to change how a piece of software program or "app" works.

Opennsource software is software with source code that anyone can inspect, run, copy, modify, and enhance.

Now, "Altcoin" is a combination of two words; "alt" and "coin". 

The word "alt" is short form of alternative and "coin" means uh coin.

So the word altcoin, comes from the idea that all other cryptocurrencies are considered "alternative" coins to Bitcoin (BTC), the original Cryptocurrency 

Altcoins are percieved to be attempts to either take the place of or improve upon Bitcoin.

A benefit of open source software like Bitcoin is that anyone in the world can take the original codebase and try to improve or extend the software's functionality. 

With Namecoin (NMC) being the first ever altcoin, it's mission was to provide a descentralized domain name service (DNS) system.

Instead of websites being limited to using domains ending with ".com" or ".net", which were under control of ICANN (the main governing body for domain names), it (NMC) created the ".bit" domain that is independent of ICANN and could not be censored or shut down.

For example, instead of using " spurprotocol.com", I could register "spurprotocal.bit" by buying it with some NMC and use it as our URL instead.

With Namecoin as the first altcoin, it definitely wouldn't last. Within a couple of years, hundreds of alcouns were introduced to the public and then thousands.