Darker cells mean a higher score for this topic on that metric.
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Last reviewed Sources & creditsMedia creditsMethodology
Quick answers
When should I pick Line chart?
When the story is: trends, seasonality and a few series over time.
When should I avoid Line chart?
Skip it in cases like: unordered categories, or more than about four overlapping series.
Who invented or popularised it?
William Playfair, 1786 — later refined for meteorology and markets
What does it encode?
position of a polyline through ordered time
Is it OK in ads?
Yes if one claim is visible at a glance in Meta, Google and retail print; otherwise link to a full figure.
Will a teacher accept it?
Yes for lab reports and poster boards if axes, units and a source line are present.
Line chart encodes values as position of a polyline through ordered time. William Playfair, 1786 — later refined for meteorology and markets.
In reports, ads and assignments it fits trends, seasonality and a few series over time. Skip it when unordered categories, or more than about four overlapping series.
Parts
- Mark — The core mark of Line chart is position of a polyline through ordered time.
- Scale — The scale must show zero (or a declared break) and units.
- Axis — Axis titles name the variable, not a mood.
- Legend — A legend is weaker than a direct label. Write beside the mark when you can.
- Label — Numbers are optional. If comparison is the job, label the ends only.
- Grid — Keep the grid faint. Data should own the ink.
- Annotation — One annotation sentence. Date the source.
- Frame — A thin frame. Never a 3-D box.
Variants
- Time series — Variant 1 of Line chart (Time series). Same encoding, different layout.
- Trend line — Variant 2 of Line chart (Trend line). Same encoding, different layout.
- Playfair line — Variant 3 of Line chart (Playfair line). Same encoding, different layout.
- Line chart 4 — Variant 4 of Line chart (Line chart 4). Same encoding, different layout.
Labels
- Axis — On Line chart, make Mark readable.
- Legend — On Line chart, make Scale readable.
- Label — On Line chart, make Axis readable.
- Grid — On Line chart, make Legend readable.
- Annotation — On Line chart, make Label readable.
Line chart: honour position of a polyline through ordered time, and switch when unordered categories, or more than about four overlapping series.