Age and Basic Requirements
Players must be at least 18 years old to play in the NHL. There is no maximum age limit. Players do not need to be Canadian or American citizens; the NHL welcomes players from any country. Players must be in good physical and mental health to pass team medical examinations.
Draft and Signing Process
Most players enter the NHL through the annual NHL Draft, where teams select eligible players. Players can be drafted between ages 18 and 20 in most cases. Alternatively, players can sign as free agents if they are not drafted. Once selected or signed, a player must negotiate and sign an official NHL contract with the team.
Common Development Paths
Many NHL players develop their skills in junior hockey leagues such as the Ontario Hockey League (OHL), Western Hockey League (WHL), and Quebec Major Junior Hockey League (QMJHL) in Canada. Others play college hockey through NCAA programs in the United States. Some international players come from professional leagues in Europe, Russia, Scandinavia, or other countries.
Legal and Contractual Requirements
Players must comply with all NHL rules and regulations. A valid contract must be signed between the player and an NHL team, which includes agreeing to league rules, testing policies, and conduct standards. Players must also pass background checks and meet any visa or work permit requirements for playing in North America.
Special Circumstances
Players who were previously drafted but did not sign can re-enter the draft in certain situations. Undrafted free agents can try out for teams or sign directly if a team offers them a contract. International players may need to navigate additional requirements related to work visas or immigration status. 
Answer