This week, The 7 is focused on special commemorative patches worn on NHL uniforms over the past season — some of which are still being worn now in the playoffs. These patches can represent many things, but fit nicely into seven categories.

1 // The First Year

Some patches are worn to commemorate an inaugural season — like the Vegas Golden Knights. I don't think I've ever seen an inaugural season patch on the jersey of a team in the process of sweeping its first-ever playoff series. But here we are.

Expansion teams aren't the only one to mark a milestone debut season. The more common form is actually a team's first year in a new arena. The Detroit Red Wings moved out of Joe Louis and into Little Caesars Arena last fall and wore this patch all season.

2 // Milestone Markers

Significant anniversaries are another reason we often see teams wearing special patches. During the 2016-17 and 2017-18 seasons — specifically during the calendar year 2017 — all 31 teams wore the NHL Centennial patch on their right sleeves to mark the league's 100th anniversary.

This year, the Dallas Stars and Tampa Bay Lightning each wore 25th anniversary patches, despite arriving in their respective cities a year apart — Dallas in 1993 and Tampa in 1992. For the first half of the season, the Bolts only wore the 25th patch on their blue home jerseys. (You'll see what they used on their road jerseys in a moment.)

Last in this category, the Boston Bruins and Montreal Canadiens celebrated the 60th anniversary of Willie O'Ree becoming the first black NHL player. The patch was worn by both teams for one game on Jan. 17 in Boston. The Bruins won 4-1.

3 // Special Occasions

Big events often call for jersey patches. To celebrate hosting the 2018 NHL All-Star Weekend, the Tampa Bay Lightning wore a patch on their white road sweaters only — their home jerseys featuring the 25th anniversary logo as mentioned above. When they returned from the All-Star break on Jan. 30, the Bolts reverted to using the 25th patch on both uniforms.

On Nov. 10 and 11, the Colorado Avalanche and Ottawa Senators met in Stockholm for a pair of regular season games as part of the 2017 NHL Global Series. For these two games only, both teams wore patches featuring the event logo.

I suppose you could also include the NHL 100 Classic, Winter Classic, and Stadium Series patches in this category, but they were all worn on special event jerseys — which were featured a few weeks ago in the first edition of The 7.

4 // Raised to the Rafters

This topic also got its own edition of The 7 a couple weeks ago. Often when teams retire a player's jersey number, the team will wear a patch for that special night. Five of the teams that retired a number this season did just that.

The Dallas Stars honored Jere Lehtinen, the New Jersey Devils honored Patrik Elias, the New York Rangers honored Jean Ratelle, the Philadelphia Flyers honored Eric Lindros, and the Tampa Bay Lightning honored Vincent Lecavalier.

5 // Hall of Famers

Every year, a handful of hockey legends are immortalized with induction into the Hockey Hall of Fame in Toronto. To mark the occasion, every November the Toronto Maple Leafs host the Hall of Fame Game, where the latest inductees are honored. The Leafs and their opponent wear a special Hall of Fame patch. This year the game took place on Nov. 10 against the Boston Bruins. The Leafs won 3-2 in an OT thriller.

In addition, because the Anaheim Ducks had multiple players being inducted into the Hall of Fame, they hosted their own special night for Paul Kariya and Teemu Selanne. The celebrations included a patch on the Ducks' uniforms on Nov. 19. The Ducks beat the Panthers, 3-2.

Some franchises even have their own team Hall of Fame. On Nov. 14, Dale Hawerchuk was inducted into the Winnipeg Jets Hall of Fame. To mark the big night, players wore a patch in the shape of a shield with Hawerchuk's No. 10 in the middle of it.

6 // In Memoriam

Some specialty patches are meant to honor the memory of a person who played a significant role in a franchise. Mike Ilitch, who purchased the Detroit Red Wings in 1982, died in February 2017. Throughout 2017-18, the Wings wore a patch on their left shoulder that read "Mr. I" to celebrate his contributions to the club.

When legendary goaltender Johnny Bower died on Dec. 26, the Toronto Maple Leafs wore a special jersey patch for four games from Dec. 28 to Jan. 2.

7 // Bigger Than Hockey

Finally, some patches are worn to honor people and events that transcend the game. On Feb. 14, a high school shooting left 17 students dead in Parkland, Fla. This event hit close to home for the Florida Panthers, who wore a special patch on their right sleeves from Feb. 17 until the end of the season — a total of 28 games. The patch read "MSD" for Marjory Stoneman Douglas, the name of the school.

There's another edition of The 7 in the books. Hope you enjoyed this one. You probably saw a few of these patches over the course of the season. Anyone recall seeing all of them? To be honest, I'd be surprised if there was anyone quite as anal as me out there!