What Is Data Visualisation?
Data visualisation turns numbers into charts and graphics that humans understand instantly. Learn which chart type to use when.
Key Takeaways
- Visualisation makes patterns visible that tables of numbers hide
- Line charts show trends over time; bar charts compare categories
- Pie charts are almost always the wrong choice for business data
- The best visualisation is the simplest one that answers the question
Why visualise?
The human brain processes visual information roughly 60,000 times faster than text. A table of 12 monthly revenue figures forces mental arithmetic to spot a trend. A line chart of the same data makes the trend visible in under a second. Data visualisation makes patterns, outliers, and relationships visible to the human eye.
Line charts
Line charts show how a metric changes over time. They are ideal for any time series data: daily revenue, weekly active users, monthly churn rate. The continuous line implies continuity — that there is meaningful data between each plotted point. Use them when the direction and rate of change is what you care about.
Bar charts
Bar charts compare discrete categories — revenue by product, customers by country, refund rate by SKU. Horizontal bar charts work better when category labels are long. Grouped bars let you compare two metrics across the same categories. Bar charts are the workhorse of business data visualisation.
Avoid pie charts
Pie charts are almost universally the wrong choice for business data. The human eye is poor at comparing slice sizes. A bar chart of the same data is always easier to read. The one exception: two categories showing a simple majority — a donut chart showing 73% vs 27% can be effective.
The simplicity principle
Every visual element that does not convey information is clutter. Remove grid lines that are not needed. Use colour sparingly — one highlight colour, not a rainbow. The best data visualisation is the one that answers the question with the fewest elements.