What is the difference between a legend or a key? Is it still called a legend if it is located at the top, rather than the bottom of results?

4 Answers 4


"Legend" implies that its entries are generics, as with terrain types on a map, while "key" implies that its entries are specific, as with one symbol designating the Museum of Natural History, another the Metropolitan Museum of Art, etc. Generally, nobody is going to get real mad no matter which you use. It doesn't matter where they're located.


A "Caption" used to be a box you put at the top of a map, hence the "Cap" part. Today, Wikipedia still requires a Map Caption and provides a template with the following explanation: "Template intended to simplify adding a standardized and formatted caption below a map indicating the location of something (e.g. a country), possibly referring to the map's main region and optionally also to a shown subregion." They place this caption below the map.Template:Map caption

The "Legend" is the explanatory information within a Caption that allows you to understand how to use the map, defining the meaning of the symbols, especially the Keys. It is a syllogistic synopsis, a short story if you will."Building a Legend | GEOG 486: Cartography and Visualization". www.e-education.psu.edu.

The "Keys" are the symbols and numbers within the Caption that the Legend explains, and they tend to be part of the map's Legend.Map Key — Definition, Symbols, and ExamplesHow a Map Key Works

Somehow the two got mixed up over the centuries.

Imagine if you had a Caption with Keys but no Legend to explain what they mean. These types of maps are actually all too common. They are fun and challenging but sometimes impossible to understand because you have to be a bit of a cryptologist to decipher what the symbols mean sometimes. We've all seen the dotted line which represents a trail, a straight line a road, a wavy line a river, a circle with a triangle in it a campground, a skull and bones something dangerous etc.

Now imagine if you had a Caption with a Legend but no symbols. These maps exist too, as the explanation could be about shaded areas on the map with no need for designating symbols.

Somehow the Legend came to be called the "Key", which is bizarre, as if the map had a single symbol. Just as odd, some Captions are called the "Compass" which is actually the Rose Compass, which is a diagram explaining the cardinal directions relevant to the map.

This is a description of ArcGIS Pro which allows you to create Legends, Captions and Keys in maps with bivariate color symbology: "The tools in ArcGIS Pro give you great flexibility in presenting the information in your map. To more effectively communicate your message, you may want to modify the text for titles or labels, rearrange graphic elements, or add a caption that identifies the data source. Map marginalia, such as legends, scale bars, and north arrows, help explain or support your map’s message. Effective legends make the symbology used in the map clear and eliminate confusion".Customize Legends in ArcGIS Pro

Maps and their marginalia are modernly organized into five basic parts: the Title and Headings (the old Caption); the Legend & Keys; the Scale Indicator; the Grid; and the Compass Rose or North Arrow.5 Basic Parts of Any Map

  • 5
    First off, welcome to English.se. It'd be helpful to see this substantiated. Can you source this answer in some way?
    – virmaior
    Mar 11, 2014 at 2:41
  • Sounds familiar, mb what I learnt in Waldorf school as a kid. A legend defines generic/diffuse map features/zones not specific places: striped/colored areas, could be forests, regions of control, and lines/dots/dashes could be roads, rivers, paths taken by famous people; keys are nameable, geographically centered places/features that don't represent well as areas or straight/curved lines: stars for capitals, circles of different sizes for cities of relative size, waterfall symbols, a tree symbol for a Named Tree of interest, a house that's a historic landmark... Jan 26 at 7:46

A legend is a caption, a title or brief explanation appended to an article, illustration, cartoon, or poster.
A key is an explanatory list of symbols used in a map, table, etc.

Legend is more generic, while key is more specific. Neither word implicates anything about the location of the text/list.


A legend explains symbology and iconography on a map. For instance, a cross icon may symbolize the location of a church, or a heavy black line may represent a highway. A key on the other hand, conveys the meaning of thematic information. Thematic information would be something like an area being colored in a certain way to identify a statistical attribute (e.g. a choropleth map that shows California colored blue and Texas colored red to communicate political affiliation).

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