Let us assume that the bid price is $10 the ask price is $20. We can only buy for $20 and only sell for $10.
Does the current price have to be in the middle? IOW, does it have to be $15? Or can it be $14 or $16 as well?
Who sets bid and ask prices? Do market makers still exist or is everything driven by orders now?
Can the spread change but the price be unaffected? For example, can the current price be $15 as before, the ask changes to $25, and the bid drops below $10? Or is that very unlikely?