What, specifically, needs explanation? You do understand simple economics eg. how demand and supply impacts price, right?
Well for starters, there has been a long running theory - some will say conspiracy theory - that the big banks, JP Morgan in particular, has essentially cornered the trading of silver on the commodities exchanges. I don't know, seems implausible (see the Hunt Brothers, they went broke trying to corner silver decades ago). But they may in fact handle the bulk of the trading and/or clearing of trades in the exchange. Normally, an investment bank's clearing/market making desks don't take a position, they just make money from spread between bid price and ask price, and commissions. But the (conspiracy) theory is that they are massively short silver as a means to prop up the US dollar. It gets complicated for an 8 year old after this.
When you short a stock, it basically means you are borrowing the stock from someone else, sell it into the market today hoping the price will go down in the future, after which you can buy it cheaper and return the borrowed shares. The same would be true somewhat for commodities like silver. You can short silver at $27, and if it drops to $23 you can buy it back and pocket the difference.
Anyway, I think it is pretty well proven that there are exploits in the stock market that have been used by short sellers (people betting the stock will go down) and recently, as in GameStop, there was so much money betting on the short side that there were no more shares truly available to short. It gets more complicated from there, even in such a situation it is still possible to short more using options and if you are a big player your bank will "work with you", but the fewer shares available to borrow it gets incrementally harder to short more. What the reddit flash mob did was notice that the short interest in GME was so high that if they could gather enough people to bum-rush the market to buy GME shares in a very short period of time, it would drive the price up and the short sellers would be on the hook for potentially infinite losses. So when GME went from $20 to say $60, the shorts lost 200% of their investment and had a decision to either short more, or buy back in. The problem is for shorts is that you need 100% collateral so if you are short at $20 you need $20 in cash or equity value. And if the stock goes to $60, you need $60 in cash or equity value. So it can get almost as expensive to hold the short position as it is to cover if you don't have lots of liquidity. Eventually many of the shorts in GME capitulated and "bought to cover" to close out their short positions at a loss (because they wanted to cut their losses, or because they didn't have excess cash/equity reserves), thus increasing the demand for shares higher than the flash mob demand created, and thus pushing the price higher still. As they are buying to cover in a market where a flood of new long investors are coming in you have what they call a 'short squeeze' where the shorts are pretty much forced to buy back the borrowed shares at the much higher price. From $20 to $325 (or, $480 I think at it's mid-day high), it's a massive loss that few people can bear. There are more dynamics (such as when the price goes from $20 to $60, new shorts want to come in and the cycle perpetuates). That's the squeeze.
Long story short, some are speculating that this flash mob is going to try to do the same to the silver market, betting that there exists an oversized short position in silver and that by going long they can squeeze the silver shorts, in particular JP Morgan.
If you have questions fire away or send a PM. This board has a lot of very knowledgeable people. Crowd-sourced knowledge, just like "crowd sourced" flash mob of investors :-)
Thanks, just saw your explanation. The eight year old is learning a little bit by bit.
Now motive...other poster said to bankrupt the corrupt banks.