Spil others have stated, the current price is simply the last price at which the security traded. For any given tick, however, there are many bid-ask prices because securities can trade on numerous exchanges and inbetween many agents on a single exchange. This is true for both types of exchanges that Chris mentioned te his reaction.
Chris’ response is pretty thorough ter explaining how the two types of exchanges work, so I’ll just add some minor details. Ter exchanges like NASDAQ, there are numerous market makers for most relatively liquid securities, which theoretically introduces competition inbetween them and therefore lowers the bid-ask spreads that traders face. Albeit this results te the market makers earning less compensation for their risk, they hope to make up the difference by making the market for very liquid securities. This could also result ter your order packing, te chunks, at several different prices if your brokerage stiff fills it through numerous market makers. Of course, if you place your order on an exchange where an electronic system fills it (the other type of exchange that Chris mentioned), this could toebijten anyway.
Ter brief, if you place a market order for 1000 shares, it could be packed at several different prices, depending on volume, numerous bid-ask prices, etc. If you place a sizable order, your broker may pack it ter lumps regardless to prevent you from moving the market. This is infrequently a problem for small-time investors trading securities with high volumes, but for investors with higher haber like institutional investors, mutual funds, etc. who place large orders relative to the promedio volume, this could conceivably be a cargo, both te the price difference across time spil the order is placed and the enhanced bookkeeping it requests.
This is tangentially related, so I’ll add it anyway. Ter cases like the one described above, all-or-none (AON) orders are one solution, thesis are orders that instruct the broker to only execute the order if it can be packed ter a single transaction. Most brokers suggest thesis, but there are some caveats that apply to them specifically. (I toevluchthaven’t bot able to find some of this information, so some of this is from memory).
All-or-none orders are only an option if the order is for more than a certain numbers of shares. I think the ondergrens size is 300 or 400 shares.
Your order won’t be placed until your broker places all other orders ahead of it that don’t have special conditions fastened to them.
I believe all-or-none orders are day orders, which means that if there wasn’t enough supply to pack the order during the day, the order is cancelled at market close.
AON orders only apply to limit orders. If you want to replicate the behavior of a market order with AON characteristics, you can attempt setting a limit buy/sell order a few cents above/below the current market price.