The first Elo is a rating system that was used in chess. Elo rating system is a method of calculating the relative skills of players in games such as chess. It is named after is Hungarian creator, Arpad Elo.
This very similar Elo rating is used as a booster in gaming sites nowadays, especially online games. Elo booster is a way used by expert gamers or champions as known in the site. The player has the liberty to choose the champion they want that will play on their behalf as well as the game and rank they desire to reach. The order can be customized and booster can be prioritized.
Within these leagues, there are ranks which help prioritize and give a hierarchy to the orders that help the champions to attain the goal accordingly. There is Iron, Bronze, Silver, Gold, Platinum, Diamond, Master Tier, Grand Master, and Challenger. These hierarchies are listed as above from below to top-level respectively. Challenger level takes a player at the top level the player chooses the level they are currently in and then they decide the desired rank they want the champions to help them get into. This boosting of ranks from bottom to rank or more hire is Elo Boosting.
League of legends also provides coaching; the top rankers charge a certain amount according to the rank they hold. The higher the rank, the more expensive they charge for coaching.