You can find maps of small areas, like a yard, or vast expanses, like an entire country. There are even maps that show the whole galaxy. The key to reading any map is in understanding the scale and how it explains the relationship between actual distances and those on a map.
Maps are small drawings that explain large areas. In order to make sense of a map, all of the items pictured must be proportional to the real-life counterparts. This means that if there are 20 miles between one building and another, the map of this area must represent a proportionate distance between those items. Since all maps are made with a different purpose in mind, this proportion (ratio) may change from one map to the next. Check the "map scale" to be sure what ratio is being used. The scale of a map may be in the form of a statement, graphic line or numeric equation and can usually be found in the corner of a map.
If the scale says "1 inch = 1 mile," you know that every inch on the map represents one mile in actual distance on Earth. One-to-one is a small scale, perfect for street maps where you don't have to show a large area. Larger scales are used to show states, countries, continents or whenever you have to fit a lot of information onto one page.
If you are making a map, the scale must be precise and reproducible. Be consistent, if you begin with a ratio of 1 inch to 1 mile continue with that scale, or adjust the entire map accordingly. Don't try to approximate distances, use a ruler on paper and an appropriate measuring device when taking full-scale measurements.