I don't understand how sidechains work, or how any fee system for them works, or if sidechains have been developed yet. Can someone post a really simple explanation of what they are?
A side chain is like an altcoin but it is linked to bitcoin. You can send BTC to the sidechain and withdraw it from the sidechain.
You send bitcoin to a bitcoin address and then you get credit on the sidechain. The money in the bitcoin address is held at a multi-sig address.
When you are done, you can transfer any credit back to bitcoin. The functionaries that control the multi-sig address send you the BTC you sent back.
If a (super?-)majority of the functionaries conspire, they can steal that bitcoin.
You start with money on the bitcoin network.
BTC: 1.0 BTC
Side: 0 BTC credit
Transfer 0.5BTC to 3
(multi-sig) on the bitcoin network.
BTC: 0.5 BTC
Side: 0.5 BTC credit
You can use your 0.5 BTC credit on the sidechain and send/receive on the sidechain. They are proposing to use it for exchanges.
To withdraw your money, you tell your sidechain client to send it back to bitcoin. This happens in 2 steps.
First you lose the sidechain credit
BTC: 0.5 BTC
Side: 0.0 BTC
Next the money in the 3 address (yours and anyone who sent money to the sidechain) is used to send you the 0.5BTC back.
BTC: 1.0 BTC
Side: 0.0 BTC