The forest is the original biome that encompassed all of the map when the game came out. Currently, it covers about 1/3 of the map and is the smaller of the two biomes. The forest is the basis for survival, as it has a much warmer climate with less powerful mobs. All players spawn in the forest and work their way towards the winter.
The forest is advantageous for players because it is warmer. It also provides players with basic resources and food for survival. The forest is currently the only biome that allows players to plant berries. Players are also able to move faster in the forest.
The forest can be disadvantageous for players mainly due to the amount of players there. There is competition for resources and points. Also, the forest does not give the higher tier resources of diamonds, amethyst, dragon hearts, and winter fur.