National Teams consist of the best players, in the opinion of the National Coaches, from each country in two categories: the U20 national teams, which are for players up to 20 only, and the Senior national teams, which are for players of any age.
U-20 National Teams
U-20 National Teams consist only of players below 21 years of age from (born in) the national team's country. In most countries, only the players that are pulled as 17 year olds in the first weeks of the season stand a chance to be trained to a high enough level to be selected before they turn 21. In large countries, this often means only players who are aged 17, with an excellent main skill pulled on the very first week of the season are suitable U20 material. As such Week 1 excellent players are highly prized, and are sold for incredibly high prices.
National Teams are able to select players of any age, as long as they are of the same nationality as the National Team. The skill level required for a player to make it into the national team differ from country to country, and is primarily based on the age and size of the country in Hattrick. In the larger countries a player typically needs to be near divine in one of his primary skills in order to make it.
The Senior Team's national coach is elected every two seasons by the users of the country the team is from; the election is staggered to happen on different seasons than the U-20 elections.
National Team Players
Players gain experience by playing in national team matches. As well, a national team player will earn a salary reduction, when playing in a national team match, of 33-40% depending on whether or not he is playing in his home country.
On the players page of their club they are accompanied by a flag of their country. Furthermore the page of the specific player mentions the following: "Also part of Team ...!"
Most of the time having a national team player is considered an honour. Many teams around the globe fully dedicate their teams to training U20 and/or NT players. However farm teams are disliked by many.
National Team Database
The National Team Database is the website that most national team managers use to keep track of their national players pool.