Every element on the canvas has a meaning.
What each visual layer in the explorer tells you — from the source band at the top to the cursor line you drag through time.
Terms in this category
The coloured strip across the top of every chart that shows which dataset covers each era.
The source band is divided into four zones: Historical reconstruction (hatched), Compiled history, UN estimates, and Projections (hatched). The hatch pattern signals lower certainty. Seam lines mark the transitions between zones.
One country's population history drawn as a filled hill-shaped band on the canvas. Height = population. Color = world region.
Each country gets its own horizontal lane. The filled area shows population over time; the line at the top traces the exact value. Countries are stacked by peak population size — largest at the top. Lanes can be zoomed, filtered, and pinned.
The gold vertical line that marks the current year. Drag it to move through time.
The cursor controls which year the inspector panel reads from. You can drag it directly on the canvas, use the scrubber at the bottom, or type a year. On mobile, the cursor only appears while your finger is pressing the canvas.
A dashed vertical line marking where one source dataset ends and the next begins.
Seam lines appear at roughly 1800 (HYDE to Gapminder) and 1950 (Gapminder to UN WPP). Values on either side of a seam are from different methodologies, so apparent discontinuities may reflect the source change rather than a real population event.
How years are spaced on the horizontal axis — linear, weighted, or logarithmic.
Linear spacing gives every year the same width. Weighted spacing compresses ancient history and expands the modern era, making recent trends easier to read. Logarithmic spacing gives proportional visual weight to each decade. The default is weighted.
Each country's ridgeline is sized relative to its own highest population value, not a shared global scale.
This lets small countries like Iceland appear alongside China without being invisible. It means lane height cannot be directly compared across countries — a tall Iceland lane does not represent the same population as a tall China lane. The inspector shows exact numbers.
A country card you keep fixed on screen so you can compare it against the rest of the canvas.
Pinning locks a country's inspector panel open while you scroll or filter the main canvas. You can pin multiple countries to compare their population trajectories side by side.
Whether population is shown using today's borders or the political boundaries that existed at the time.
Modern border mode shows population within a country's current territory, even for historical periods before that country existed in its current form. Former border mode uses the political entities that actually existed at each point in time — relevant for studying empires, splits, and unifications.
Common questions
Why does the cursor only appear when I press the chart on mobile?
On a small screen, a persistent cursor line clutters the chart and makes ridgelines hard to read. Showing it only on active touch keeps the chart clean while still letting you scrub to any year you want.
What does it mean when a line is dashed?
Dashed lines indicate projections — UN median-variant forecasts for 2025–2100. They are not observations. The hatched source band above the chart confirms when you have crossed into the projection zone.
Why are some countries much taller than others even though their populations are similar?
Ridgeline lanes use own-peak scaling by default, which sizes each country relative to its own maximum — not a shared scale. This is intentional so small countries remain visible. Hover over a lane to see the exact population value from the inspector.
What do the different time lens modes do?
Linear mode gives every year equal horizontal space. Weighted mode (the default) compresses ancient history into a smaller share of the axis and expands recent decades, making modern trends more readable. Log mode gives proportionally equal visual weight to each order of magnitude in time.
How do I reset the view to the default?
Use the "Reset all" button in the filter panel on the left. This resets the time range, selected countries, time lens, and cursor year to their defaults. The URL will also update to reflect the reset state.
Can I link to a specific view?
Yes. The URL updates automatically as you change filters, cursor year, and zoom level. Copy the URL from your browser's address bar, or use the Share button in the top bar to copy it to your clipboard.