You can simulate a network of peers by opening multiple browser tabs. Each peer can mine blocks and make transactions independently and the resulting blockchain will resolve conflicts correctly across all tabs.
A blockchain works by laying down a chain of blocks of transaction data.
Each block in the chain contains a cryptographic hash with two important properties:
It proves a link to the previous block.
It proves that difficult computational work has been done.
The proof-of-work is accomplished by iteratively updating a nonce until a low-probability hash is discovered.
These two properties mean a blockchain is digital amber.
If somebody wants to modify a transaction deep inside the amber it would be very difficult because they would have to re-create every layer of the blockchain by doing as much work as the original process required.
In my browser blockchain the hashing is implemented like this:
A couple of years ago my friend Joe recommended this stuff called
Plastimake to me.
It is a hard plastic which goes soft and malleable at around 60 degrees
celcius. You drop some in boiling water until it goes clear and soft and
then you can mold it into whatever shape you want. It cools and hardens
again quickly in whatever shape you have molded it into. You can re-heat
it to soften and re-use it again.
Scout and I have used it several times to hand craft little figures for
play. I've also used it around the home and when prototyping things as
it's a very quick way to get a hard plastic into exactly the shape you want.