Charts

Charts are graphical representations of data that aim to communicate information quickly and clearly. They translate numbers and categories into visual formats that reveal patterns, trends, and relationships that might be less obvious in raw data. Common chart types include bar charts for comparing quantities across categories; line charts for showing changes over time; pie charts for illustrating proportional parts of a whole; histograms for the distribution of a continuous variable; scatter plots for examining relationships between two variables; area charts for cumulative totals; and heatmaps that display values across two dimensions with color encoding. Other varieties include bubble charts, which add a third quantitative dimension by marker size, and radar charts, which compare multiple variables on a common scale.

Design and interpretation hinge on elements such as axes and scales (linear, logarithmic, or ordinal), data series, legends, and titles. Good charts use clear labeling, appropriate color palettes, and avoid unnecessary embellishments or misleading axis manipulations. They should present data honestly, avoid distortions, and consider accessibility for readers with visual impairments.

Historically, modern data charts emerged in the 18th century with William Playfair, who introduced bar charts, line charts, and pie charts. Developments in the 19th and 20th centuries expanded chart types; today charts are created in spreadsheets, specialized visualization tools, and programming libraries.

Charts are used across journalism, business analytics, science, education, and public communication to summarize data, compare options, track performance, and reveal relationships that guide decisions.