Length is one of the most important aspects of Slither.io. The length of your snake, which also determines its size, is displayed as a number in the lower right-hand corner of the screen. To increase your snake's length you must eat pellets, either those randomly generated by the game (which give a small amount of length) or by eating the remains of other unlucky snakes who have died (typically giving much more length than individual pellets).
Ranking and Leaderboard
Along with your current length, you are also shown where you rank among other players on the server. Typically this is shown as "X of Y Players" where X is your current rank and Y is the total number of players in your game.
The Leaderboard shows the current lengths and names of the top 10 longest snakes in the game.