Pushing

Pushing is the process of clearing enemy creep waves and building up large allied creep waves in order to take down enemy buildings.

The advantages of Pushing
Ultimately, pushing is necessary to win the game. Deciding when to push is a crucial part of the team's individual strategy, as some lineups reach their peak in the late game, while some lineups have the capability to finish the game very early.

Early pushes put pressure on the enemy team by forcing them to defendend their towers. This is an effective way to counter Carry Heroes, because they require some time and farm to become effective. Killing towers is also a good way to earn money for the whole team, as every Hero gains bounty.

Heroes
Summoning abilities, such as Venomancers Plague Wards or Nature's Prophet's Nature's Call are excellent pushing abilities, as the summons can attack enemy creeps and buildings, as well as absorb large amounts damage. Spammable AoE Nukes like Death Prophet's Crypt Swarm or Shadow Shaman's Ether Shock can quickly take down hostile creep waves and can keep up the push in this way. Heroes with AoE healing abilities, such as Necrolyte's Death Pulse or Dazzle's Shadow Wave can drastically boost the durability of allied creeps and sustain a push. Some abilities, like Leshrac's Diabolic Edict and Pugna's Nether Blast can even deal direct damage to towers.

Items
Most pushing items provide buffs or heals to allied units, allowing creeps to deal more damage and survive longer. However, they also allow Heroes to stay far away from their Fountain for extended amounts of time, so they can keep up the push. One or two Arcane Boots and some heals basically make the Fountain obsolete and the whole team can stay outside and gank or push. The Necronomicon provides both a useful aura and two summoned units that can aid the push. In the later stages of the game, Carry Heroes can quickly push lanes by themselves. Items that hit multiple units, like Battle Fury or Maelstrom can boost their ability to push the lane even more.