Honor is a relaunched system introduced to League of Legends in patch V7.13. The Honor system is used to incentivize positive behavior among the League of Legends community and indentify players who give a positive gameplay experience to others in the game. Honor gives many rewards and has a five tier system for these rewards.
Players can only honor other players in matchmade games (including Co-op vs AI), as this feature is unavailable for Custom games.
- Stayed Cool: Tilt-proof, chill.
- Stayed cool is the Honor meant for a teammate who stayed calm and was a provider of a positive playing experience.
- Great Shotcalling: Leadership, strategy.
- Great Shotcalling is the Honor meant for a teammate who had good leadership and was able to lead your team to a triumphant win or a gracious defeat.
- GG <3: Team player, friendly.
- GG <3 is the Honor meant for a teammate who was Honor worthy but didn't fit into a neat and tidy box of what they did to earn it.
Honoring a Player
The Honor vote lies between the Nexus cracking and the end-of-game screen. The big change is that each player can now only honor one teammate; a shift that helps make each honor feel more weighty on both the giving and receiving ends. Note, you cannot Honor yourself.
Everyone starts at Honor level two and can move up to level five, or down to the quite dishonorable level zero by getting slapped with penalties. A quiet, hard working player will level up and earn rewards even if they earn fewer honors overall. And as you'd expect, a standout player who earns honor more frequently will rise a little more quickly. This means you do not need to be fake nice to earn rewards or level up.
- End of Season Rewards:
- Just like Ranked, Honor grants exclusive rewards at season's end for those who put the work in. The renewed Honor will be a pillar for League of Legends long after you first get to play with it. Details on the rewards are to be announced later in the 2017 Season.
- Key Fragments:
- Originally dropping randomly after wins, Key Fragments are now exclusive to Honor, All you need to do to earn them is get games in and be a solid teammate. They will drop randomly in the end of game screen or login.
- Honor Capsules:
- Starting at level three, Honor Capsules start to drop as well. You can expect an Honor Capsule to occasionally drop instead of a regular key fragment. Honor Capsules require no key to open and unlock a couple key fragments at a minimum. Beyond that, Honor Capsules give a moderate chance at champion shards and a rare shot at the now Honor-exclusive skins Medieval Twitch and Grey Warwick. The two skin drops are permanents, and unlock the champion if you don't already own them.
- Loading Screen Flair:
- Once you hit Honor level three, you're eligible for temporary loading screen flairs. Unlock your flair by earning Honor from your teammates. If you receive two Honors from premade teammates, or just one from a non-premade teammate, you'll bring a loading screen flair to your next game. The flair lasts one game, but there's no cooldown. So shoot for a streak of honors to consistently keep your flair. As you move to levels four and five, your loading screen flair levels up with you.
Below is a list of the rewards available at each level tier:
Old Honor System
Discontinued in Patch V7.13, Honor used to be a 4 tier system which lacked rewards and became rather obsolete in Season 6 and 7.
- Old Honors
- Summoners who would be honored through this category are those that have a positive impact on your game and make the match enjoyable, win or lose.
- This category is for summoners that share their know-how and actively help other players improve their gameplay.
- Honorable Opponent:
- Honorable Opponents are players from the opposing team that remain humble in victory or graceful in defeat and/or behave in a positive manner throughout the game. This is the only category where a player can receive a crest without any points in the other categories.  The crest awarded is red.
- This category honors players that put the team ahead of themselves. This includes anything from forming great plans, helping struggling lanes recuperate, and more.
- Honoring A Player
Honor allows you to acknowledge other summoners that have had a positive role in any of your matchmade games. Similarly to reporting a player for negative behavior, you can honor others at the result screen at the end of a match. By clicking on the green "Thumbs Up" button next to a summoner's name, you will be given a choice out of three of the honor categories for allied players, or you may select "Honorable Opponent" when honoring enemy players. Selecting one of the options will grant that player honor in the selected category. Honoring a player makes it impossible to report the same player for negative behavior. Inversely, reporting a player makes it impossible to honor that same player. 
Do note that every summoner has a limited amount of honor to give, which is dependent on the number of matchmade games you play. This is a safety measure put in place to prevent players from trading honor or "farming" it. Players using the system responsibly and as intended will never run out of honor to hand out. Honoring players at every opportunity or trading honor will easily make you reach this limit.
Honoring friends is completely acceptable and it is encouraged if the summoner in question is truly being an honorable player. On the other hand, constantly granting honor to the same person after each match will be detected by the system and may involve consequences. In terms of unlocking crests, players will effectively be granted a different amount of honor depending on who honored them. For instance, a player that was honored by a stranger in a matchmade game will count more towards a crest than a player that was honored by a friend that they queued with, even though the counter goes up by one in both cases.
- Reviewing Honor
You can see your Honor, separated into the four categories, on your summoner profile. Honor is displayed directly above your Stats Overview and shows each category's individual values. This bar is visible to all players that view your profile, and you can see others' honor as well by visiting their summoner profile.
- Crests and Ribbons
When a player has consistently received honor in the appropriate categories, they will be presented with an animation on their summoner profile and be awarded a crest. For Honorable Opponent, this is achieved by consistently being honored in the honorable opponent category. For the remaining three crests, a combination of the honor categories must be achieved. The animations for the four crests can be seen here.
Although the official term is crest,  many players refer to crests as ribbons due to their appearance. Only a single crest will be displayed at a time, even if a player has unlocked more than one crest. The crest displayed will be the rarest out of those that the player has unlocked.   Crests are visible to other players during champion select and on the loading screen, where it will be placed on the top left corner of your box. There are four crests: Great Leader, Great Mentor, Great Teammate and Honorable Opponent.  Honorable Opponent is the only one that appears visible for the enemy team. All crests are visible to spectators. As of the late October patch (Shadow Isle), Honorable Opponent has been made viewable to both the enemy team and the player's own team during both champion select and on the loading screen.
Crests are temporary rewards designed to encourage players to remain honorable even after receiving the recognition. As such, they can be lost if players stop acting positively and no longer receive honor. Being punished by the tribunal will also remove all crests from a player, similarly to honor points.
- "Crests aren't based on Honor counts in your profile.
- Honor assesses the value of all your exchanges to determine how Honorable you are compared to the rest of the population."
Lyte also stated that the crests besides Honorable Opponent are not as straightforward, saying: 
- "Here's a secret, the base Honors (Friendly, Teamwork, Helpful, Honorable Opponent) are not 1:1 with the Crests of Honor.
- There's the Crest of Honor - Honorable Opponent that many have unlocked and yes, you just need Honorable Opponent Honors to unlock that. However, the other Crests are not so simple...
- In fact, has anyone figured out what the other Crests are even called? ;) That might give you a clue about how to earn them."
Great Mentor Crest - the crest is greenish blue - this is a combination of Helpful and Friendly 
Supportive and helpful, a Summoner that teaches players about the league.
Great Teammate Crest - the crest is green
Cooperative and works with teams to secure victory.
Great Leader Crest - the crest is yellow
Leads teams to victory through great communication.
- ↑ Status Kwoh explains the requirements for ribbons
- ↑ Reporting and Honoring cancel each other
- ↑ http://www.reddit.com/r/leagueoflegends/comments/14e9a4/honor_has_lost_its_sheen/c7cjum1
- ↑ http://na.leagueoflegends.com/board/showthread.php?p=32098178#32098178
- ↑ http://www.reddit.com/r/leagueoflegends/comments/14e9a4/honor_has_lost_its_sheen/c7cdhgt
- ↑ http://www.reddit.com/r/leagueoflegends/comments/14e9a4/honor_has_lost_its_sheen/c7ccywj
- ↑ http://www.reddit.com/r/leagueoflegends/comments/14e9a4/honor_has_lost_its_sheen/c7ccmji?context=3
- ↑ http://na.leagueoflegends.com/board/showthread.php?p=32098178#32098178
- ↑ Lyte on crests and honor
- ↑ 
- ↑ Status Kwoh explains some of the details of the crests on Reddit