Map Essentials: Titles, Symbols, Keys, and Compasses

A map is a flat, scaled drawing of all or part of Earth’s surface, and its essential parts are the title (what it shows), symbols (pictures, colors and lines standing for features), the key or legend (which explains the symbols), a compass rose (which gives direction) and a scale. In brief: to read a map, first read the title, then the key, then find north with the compass rose, and use the scale to measure. Globes show Earth’s shape accurately, whereas flat maps must distort some properties, but they are easier to carry and can show more detail.

Maps are the main tools of geography, but they only work if the reader understands their parts. This guide describes maps and globes, the titles, symbols and keys, the cardinal and intermediate directions and the compass rose, compares the map elements in a table, works through an example of finding a direction and a distance, outlines the history of maps and corrects common mistakes.

What are maps and globes?

A globe is a model of Earth as a sphere. It shows the true shapes, relative sizes, distances and directions of the continents and oceans, but it is large, expensive and cannot show much detail. A map is a flat representation. Because a sphere cannot be flattened without stretching or tearing, every flat map distorts at least one of shape, area, distance or direction, and the choice of projection depends on the purpose. Maps can show a small area in great detail, can be printed, stored and used digitally, and can show many kinds of information (relief, roads, population, climate).

What are titles, symbols and keys?

• Title: says what the map shows and where, for example “Rainfall in East Africa”. It tells you which type of information to expect. A good map also gives the source and the date.
• Symbols: small pictures, shapes, colors or lines that represent features. Point symbols mark individual features (a school, a church, a mine), line symbols show linear features (roads, rivers, railways, boundaries) and area symbols (colors or patterns) show regions (forest, lakes, built-up areas). Colors often follow conventions: blue for water, green for vegetation or lowland, brown for high ground, and so on.
• Key (legend): a box that lists the symbols with their meaning. Always check the key, because the same symbol can mean different things on different maps.
• Other elements: a scale, a grid or graticule of coordinates, a border, an inset map (a larger view of a part) and a locator map.

How do compass directions work?

Cardinal directions are north (N), east (E), south (S) and west (W), at right angles to each other. Intermediate (ordinal) directions lie halfway between them: northeast (NE), southeast (SE), southwest (SW) and northwest (NW). A compass rose is a figure on a map that shows these directions, with north usually at the top. Finer divisions give the eight-point and sixteen-point compass. A magnetic compass has a needle that points to magnetic north, which is slightly different from true (geographic) north. In degrees, a compass bearing is measured clockwise from north: N = 0°, E = 90°, S = 180°, W = 270°, and the intermediate directions are at 45°, 135°, 225° and 315°. If a map has no compass rose, north is normally at the top.

Map elements compared

Worked example: reading a simple map

1. Title: the map is titled “Main settlements and roads of Greenvale”, so it is a map of settlements and roads.
2. Key: a black square is a village, a red line is a main road and a blue line is a river.
3. Locate the places: village A is at the left (west) end of the map and village B is 3 km east and 3 km north of A.
4. Direction: equal eastward and northward distances mean B lies northeast (NE) of A, on a bearing of 45°.
5. Distance in a straight line: the straight-line distance is √(3² + 3²) = √18 = 4.24 km. By road, which runs 3 km east and then 3 km north, the distance is 6 km.
6. Another village C: 4 km east and 3 km north of A has a distance of √(4² + 3²) = 5 km and a bearing of about 53° from north (east of north), so it is described as northeast, nearer east than north.

How did maps develop?

Some of the oldest known maps are Babylonian clay tablets from about 2,500 years ago, and the Greeks introduced the idea of a spherical Earth and coordinates. Ptolemy’s work was influential in Europe and the Islamic world. Medieval European mappae mundi were more symbolic, and the age of exploration produced accurate nautical charts. Gerardus Mercator published his famous projection in 1569. Modern topographic mapping by national survey agencies began in the 18th and 19th centuries, and today most maps are digital and made with satellite imagery and GPS.

Which mistakes are common?

Mistake 1: Not reading the key

Symbols and colors are not universal. The key explains them for each map.

Mistake 2: Assuming north is always at the top

It usually is, but check the compass rose, because some maps are oriented differently.

Mistake 3: Confusing magnetic north with true north

A compass needle points to magnetic north. The difference (magnetic declination) varies from place to place and over time.

Mistake 4: Treating a flat map as an exact picture of the sphere

All flat maps distort shape, area, distance or direction. Choose a projection that suits the purpose.