What the first three characters of a VIN mean
The first three characters of a VIN are the World Manufacturer Identifier, or WMI. They say who built the vehicle. This site has a page for every one NHTSA has on file.
What each character says
The first character is a region, and with the second it is a country. 1, 4 and 5 are the United States, 2 is Canada, J is Japan and W is Germany. Other countries share a first character: KL to KR is South Korea, 3A to 3W is Mexico, and SA to SM is the United Kingdom.
The third character, with the first two, names one manufacturer and often one kind of vehicle. Honda's cars built in the United States start with 1HG. Hyundai's multipurpose vehicles built in South Korea start with KM8.
The country in a manufacturer code is where the code was registered, which is usually where the vehicle was built. The plant in position 11 is the more exact answer.
Small manufacturers use six characters
A manufacturer that builds few vehicles shares its first three characters with others. Its third character is 9, and positions 12, 13 and 14 of the VIN finish the code. On this site such a code is written as six characters: 1P9618 means a VIN that starts with 1P9 and has 618 in positions 12 to 14.
One manufacturer, many codes
A large manufacturer has many codes: one for each country, division and kind of vehicle it builds. A make's page on this site lists the codes its vehicles use.
Looking one up
Decode a whole VIN on the first page, or put the code after /wmi/ in this site's address. The same page as Markdown, for a program:
curl https://open.wenmarpro.com/wmi/KM8.md