The first criterion for connecting sellers and buyers and making a deal is price.
The lowest selling price will be executed first, and the highest buying price will be executed first.
This is a principle that applies not only to the stock market but also to general markets.
When there are many people selling one pound of pork, the one selling for 9,000 won sells faster than the one selling for 10,000 won.
It is also the same principle as when there are many people trying to buy a pound of pork, the person who wants to buy it for 11,000 won can buy the meat before the person who wants to buy it for 10,000 won.
The second criterion is time.
If the prices are the same, the principle is that the person who placed the order first will be given priority.
This applies regardless of whether you are selling or buying stocks.

The third criterion is quantity.
If the prices are the same and the order times are the same, the transaction between the person who wants to buy more or sell more will be executed first.
This means that the meat of a person selling 10 geun worth of pork will be traded before that of a person selling only 1 geun worth 10,000 won.
If you've read this far, you've essentially learned all three principles of trading that investors need to know.
I hope this answers the question, "Why isn't my order being filled when I placed it at the same price?"
--- pp.49-50

After-hours trading takes place for approximately 10 minutes, from 8:30 AM to 8:40 AM, before the market opens. A separate price cannot be specified, and transactions are concluded at the previous day's closing price.
The biggest difference between after-hours trading and other trading hours is that the person placing the order cannot directly specify the price.
In after-hours trading, the stock price is automatically determined by the previous day's closing price or the current day's closing price.
This is a system where, without having to submit a separate price, if I say I want to buy or sell, the previous day's transaction price becomes the bid price and the transaction is completed if there is volume.

--- p.73

If you're interested in investing, you've probably heard the phrase, "Use IRP and ISA accounts to save on taxes!"
The two financial products have something in common, starting from their names: they are difficult.
They all have one thing in common: they are all used to increase the assets of ordinary people.
Although the names are similar, there is a big difference in how they are operated.
You can think of them as completely different products with similar names.
An IRP is a system that allows individuals to accumulate and manage assets in preparation for retirement.
You can pay up to 18 million won per year, and you can enjoy tax savings by receiving a tax deduction at a certain rate for the amount paid.
Direct investment in stocks is not possible, but you can invest in indirect products such as ETFs.
The operating income and principal paid here can be received as a pension after age 55.
On the other hand, ISA is a comprehensive account created for the purpose of increasing personal assets.
The annual payment limit is set at 20 million won, and the total limit is 100 million won.
This is a tax-exempt investment product that allows you to hold multiple products in a single account, with the profits generated from these products being tax-exempt. While an IRP offers tax savings through tax deductions, an ISA offers tax savings through tax exemptions on profits.
Additionally, a low tax rate of 9.9% is applied to amounts exceeding the tax-free limit of 2 million won, and taxation can be deferred for up to 3 years from the time of occurrence, allowing you to enjoy tax savings.

--- pp.197-198