The word "vision" comes straight from English, where it means "sight" or "view." In Dota 2 it refers to everything that lets a team see the map: the sight radius of heroes, allied creatures and buildings, as well as special items and abilities that reveal specific areas.
Why vision matters so much
The map in Dota 2 is covered by fog of war: a player sees only what is near their heroes, buildings and allied creatures. Everything else is hidden. That is why enemy movement across the map often goes unnoticed, and this directly affects decisions: is it safe to go for runes, can you farm in the jungle, should you take a fight or fall back.
Another feature: the map has high ground. A hero standing on low ground cannot see what is happening on the high ground until they climb up themselves or until an ally or an item provides sight there. This makes vision control a separate part of the game, not a minor detail.
How a team gets vision
The main tool is observer wards: consumable items that are placed on the map and grant sight in a certain area for a limited time. They are usually bought and placed by a support player. There are other sources too: nearby heroes and allied creatures, buildings, and abilities and items that reveal areas of the map for a short time.
The flip side is denying vision. If a ward is placed, the opponent can find and destroy it. So good ward placement involves not only "where to place it" but also "how to make sure the enemy doesn't find it." The fight for vision is a constant contest: one team places wards, the other hunts for them and destroys them.
How the word sounds in the game
Players use it in all sorts of phrases:
- "no vision": there is no sight on the area in question, and nobody knows what is happening there;
- "give vision": a request to place a ward or reveal an area of the map;
- "vision on the rune": sight near the spot where runes spawn;
- "died without vision": a player died because they walked into a place where nobody could see and nobody warned them;
- "vision across the map": the overall picture of the team's ward placement.
A typical example
An allied hero goes to farm a distant neutral creep camp. There is not a single ward on the nearby approaches, and nobody on the team is looking at the minimap. Enemy heroes step out of the fog of war and kill him in a few seconds. After a death like this, the chat usually says "no vision again": this is not an excuse but an accurate description of the cause. The team had no information, and the player had no chance to retreat in time.
A well-placed ward in the same situation would have shown the enemies approaching in advance, and the hero would have had time to leave. This is exactly why experienced players see vision not as a minor detail but as one of the main tools for controlling the map.