Lanes are a major feature of the map. There are the three distinct lanes, each with their own advantages. They are identified through several different tactical approaches.
The lanes are commonly called top lane, mid lane, and bottom lane. These terms directly refer to them using their geographic location on the map.
The middle lane (often shortened to mid lane or mid) is the lane going directly from one base, across the river, to the opponent's base. It is the quickest and shortest path to each base.
The top lane (often shortened to top) is the lane going from base to base via the top left corner of the map. It runs along the left and top sides of the map. Both the Radiant and Dire refer to this lane as the top lane. It is the Radiant Offlane and the Dire Safe Lane. It is adjacent to the Dire's jungle and the creep wave often ends up fighting on the Dire's side.
The bottom lane (often shortened to bot lane or bot) is the lane going from base to base via the bottom right corner of the map. It runs along the bottom and right sides of the map. Both the Radiant and Dire refer to this lane as the bot lane. It is the Dire Offlane and the Radiant Safe Lane. It is adjacent to the Radiant's jungle and the creep wave often ends up fighting on the Radiant's side.
The mid lane is traditionally a solo lane. It involves a high degree of skill, usually involving a team's best player. The mid laner must contest last hits and denies to control the flow of gold and exp in their favor. This has the benefit of controlling the power of the enemy mid laner, while also bolstering your own strength. The player who "wins" the mid lane essentially is able to gank the side lanes successfully as well as push down the enemy's mid lane tower, gaining map control for his entire team. Much play in the mid lane also revolves around rune control and avoiding smoke ganks.
The safe lane is the lane adjacent to your jungle. Since it's longer, your creeps will take more time to reinforce, keeping the creep wave closer to your tower and on your side of the river. As a result, heroes will be safer from ganks as they can stay under their tower. If your team has a jungler, he is also near in case of emergencies and a position near the tower. For the Radiant side, the bottom lane is the safe lane, running along the bottom of the map. For the Dire side, the top lane is the safe lane, running along the top of the map.
The Offlane is adjacent to your secret shop and ancient camps. Due to the short reinforcement distance, your creeps will often end up on the opponent's side of the river, leaving you in a vulnerable position next to their jungle. Being susceptible to heroes coming through the river makes this a more challenging lane, however strategically the Offlane is usually run solo for the Offlaner to quickly gain exp to leave the lane at level 6 and gank. The name "Offlane" refers to the play style of running the lane, in which the hero is rarely seen last hitting in lane. They are instead staying "Offlane" at the safest distance possible to gain experience.
The terms solo lane, dual lane, and trilane refer to the amount of heroes occupying a lane in the early stages of the game. Combinations of the various laning terms occur to signify a specific occupation in a certain lane. For example, solo mid refers to a single hero in the middle lane.
A solo lane is when a lane has only a single hero running it. Heroes that are alone in a lane receive maximum experience and gold as it isn't split among occupants. The main risk to this rewarding strategy is that being alone makes a hero more vulnerable to ganks. In common strategy, the mid lane is always run solo and the Offlane is often run solo.
A dual lane is when two heroes team up to run a lane together. This is the most common setup for the safe lane. Usually one hero who is more farm-dependent tries to maximize their last hits, while the second hero supports the other by protecting him, harassing the opponent and getting denies.
A trilane is when three heroes run a lane together. There are two types of trilane strategies.
The aggressive trilane is three heroes in the Offlane. They try to pressure the enemy team's safe lane and disrupt the jungle. To be successful, an aggressive trilane is largely dependent on getting hero or tower kills. Aggressive trilanes
The defensive trilane is three heroes in the safe lane. Two supporting heroes make sure the third hero, their carry, gets all the farm. They push the enemy heroes back to deny them experience and gold, while simultaneously protecting their carry from the enemy. The supporting heroes can gain some experience and gold of their own by farming the jungle in the meantime.
The word trilane can sometimes also refer to the trilane setup, referring to a 1-1-3 division of heroes among the lanes. In that case, the team has two solo lanes and one trilane.
Laning is the act of staying in a lane. A hero that lanes gains gold and experience from the dying creeps, and is also protecting the nearest tower. Games generally start out with a laning phase where all or the majority of players start out in a lane. Later on more roles such as ganking, pushing, and roaming come into play, but often enough players go back to laning for a steady income of exp and gold.