Who is eligible to play in junior tennis tournaments?

Question

This is a quote from Wikipedia article on junior tennis (emphasis mine). I will also add a link to the current revision - in case the article changes in the future.)

Junior tennis refers to tennis games where the participants are aged 18 and under. Eligibility to compete is not based on age, but year of birth: as a result, some players must move out of juniors soon after their 18th birthday, while others can play juniors until they are nearly 19. Some players who qualify as "junior tennis" players also play in main adult tours, though forms signed by their parent or guardian are required for this.

Could somebody explain the rules about eligibility for junior tournaments in more detail? For example, as now is 2016, are players born in 1998 and later the ones who are allowed to compete this year in junior competitions?

It would also be nice to have some source for this. (As the Wikipedia article I linked to lacks references.)

Answer 1

Yes, according to the FAQ on the juniors section of the ITF tennis website:

Q. How old do I have to be to compete on the 2014 ITF Junior Circuit?

A. The 2014 ITF Junior Circuit is open to players born between 1st January 1996 and 31 December 2001. Players must have reached their 13th birthday in order to participate in an ITF Junior Circuit tournament. Players are able to enter ITF Junior Circuit events via their IPIN account from the age of 12 years 11 months.

The FAQ is a bit out of date (referencing the 2014 circuit), but I believe the rules are the same for 2016. Thus players are eligible to play on the 2016 ITF Junior Circuit if they were born between January 1st 1998 and December 31st 2003. A look at the more comprehensive (and recent) 2016 ITF Junior Circuit Regulations confirms this.

Note that not all federations have the same rules. For instance in the United States Tennis Association, players are considered "juniors" if they have not yet turned 18 (so they become ineligible precisely on their 19th birthdays).