80 types of charts for data visualization. Part 4: Data over Time or Temporal charts
by Ivan Kilin — Data Visualization Specialist & Dieuwertje van Dijk — Data Visualization Designer @
Date-over-time graphs are used to visualize trends and changes in data over a specific period. The X axis usually represents time, the Y axis the value shows the tracked data. Most common and useful time series chart type is line chart.
Area chart
What is an area chart?
An area chart builds on a line chart. You plot data points, connect them with a line, and then shade the space between the line and the x‑axis. The filled area shows how a total grows or shrinks over time, so the reader sees volume as well as trend.
When should you use an area chart?
Choose an area chart when you want to show the magnitude of a measure, not just its trend. The filled space draws the eye to how much has accumulated or changed over time. This is helpful for totals that start at zero, such as monthly revenue, website visits, or rainfall. Pick an area chart when the story is about “how much” in addition to “going up or down.
When you shouldn’t use an area chart
Avoid an area chart when you need to compare precise values or show small fluctuations. In this case, a simple bar chart is better to use. Moreover, the filled shape can hide fine detail, and if the data does not start at zero, the shaded area can mislead. In this case, a line chart is clearer.
Stacked area chart
Alternative name: Stacked area graph
What is a stacked area chart?
A stacked area chart shows how several groups change over time. Each group’s area is placed on top of the previous one, so the chart displays both the total and the contribution of each group at every point.
When should you use a stacked area chart?
Use a stacked area chart to show the overall trend of a total and how several groups contribute to that total over time. It works well for data that starts at zero and where the order of the series does not distract from the main message. This works, for example, for monthly revenue broken down by product line or daily energy use split by source. The filled layers let readers see growth or decline in the whole while still spotting which groups drive those changes.
When you shouldn’t use a stacked area chart
Skip a stacked area chart if the main goal is to compare the subgroups with each other rather than the combined total. Upper layers sit on shifting baselines, which makes their exact sizes hard to judge. The chart also becomes messy with many small categories, as colours blend and labels overlap. In those situations, a grouped bar chart or multiple line charts will communicate the data more clearly. Another alternative is a percent‑stacked area chart. This chart rescales each time step to 100 percent so the layers show how each group’s share of the whole changes over time.
Stream graph
Alternative names: Streamgraph, ThemeRiver
What is a stream graph?
A stream graph is undoubtedly one of the most beautiful chart types available. This stunning type of chart is a variation of a stacked area chart. Instead of piling layers on a fixed x‑axis, it balances them around a central baseline. The layers rise and fall like a flowing river, so the chart looks smooth and organic. Peaks and dips show how each series grows or shrinks over time, and the overall shape can hint at seasonal patterns.
When should you use a stream graph?
Choose a stream graph when you want to highlight broad trends in multivariate time‑series data and add visual appeal. It works well for social‑media analysis over months, web‑traffic sources through a year, stock‑market sectors, or climate indicators. The floating baseline reduces the eye’s focus on exact numbers and lets viewers see how the mix of categories shifts over time.
When you shouldn’t use a stream graph
Avoid a stream graph if precise comparisons matter. Because layers rest on a moving baseline, it is hard to read exact values or small differences. The chart also becomes confusing when you have many thin layers or highly volatile data. In those cases, a standard stacked area chart, a grouped line chart, or small multiples will be clearer.
Bump chart
What is a bump chart?
A bump chart is a line chart that shows rankings over time. The x‑axis lists time points, the y‑axis lists rank positions (1 at the top, larger ranks below). Each category is drawn as a line that rises or falls as its rank changes. Small data marks can be placed at each time point to emphasise the “bumps” where positions shift.
When should you use a bump chart?
Use a bump chart when you care about who is ahead, who slips, and how often places change. It fits sports standings, sales leaderboards, election polls, or any series where order matters more than exact numbers. Limit the chart to a handful of lines so viewers can follow the crossings.
When you shouldn’t use a bump chart
Avoid a bump chart if you need the actual values behind the ranks, because every step on the y‑axis is equal, even when the underlying differences are not. The chart also gets cluttered with many categories or frequent ties. For precise comparisons or large datasets, a regular line chart or a table is clearer.
Bump area chart
What is a bump area chart?
A bump area chart combines ideas from a bump chart and a stream graph. Each band shows the value of a category over time (area height) while its vertical position shows the rank among all categories at each moment. The bands are sorted by rank, so you see who is on top, who moves up or down, and how big each category is at the same time.
When should you use a bump area chart?
Choose a bump area chart when you need to show both how large each category is and how their rankings change. It works well for data like market share by company, streaming minutes by platform, or vote counts by party, where magnitude and position both matter.
When you shouldn’t use a bump area chart
Skip this chart if the audience cares only about rank; a plain bump chart is simpler. It can also overwhelm readers who are not used to this type of chart, or when many categories crowd the view. In those cases, use a line chart, bump chart, or small multiples instead.
Line chart
Alternative names: Line graph, Line plot
What is a line chart?
A line chart plots data points on an x–y grid and connects them with straight lines to show how a value changes over a continuous variable, most often time. The x‑axis holds the time scale (or any ordered measure), while the y‑axis shows the numerical metric you want to track. One chart can display a single series or several lines for comparison.
When should you use a line chart?
Use a line chart when your x‑axis is a continuous scale such as time and you need to show overall trends, growth, or decline. Because the scale does not have to start at zero, you can zoom in on small movements and spot patterns that a bar chart might hide. Line charts are versatile and quick to read, making them essential in finance, science, and business dashboards. They also combine easily with other visuals. Examples are overlaying bars for totals or shading under the line to form an area chart.
When you shouldn’t use a line chart
Reserve line charts for closely spaced, continuous data where trends matter more than exact values. When dates are far apart, the connecting line can imply change that never happened, so use bars or dots instead. If precision is key, switch to a bar chart or dot plot where each value is easy to read.
Moreover, a tangle of many lines soon overwhelms. Best practice is to highlight the main series and fade the rest. Finally, skip dual‑axis line charts. Two different scales on one graph mislead. It is therefore better to use two simple line charts side by side instead.
If you’d like to design really stunning line charts, make sure to see our line chart resource page full of great tips and more line chart examples.
Spline chart
Alternative names: Spline graph, Curve chart
What is a spline chart?
A spline chart works like a line chart but replaces straight line segments with a smooth curve. This curving line gives the trend a softer, more continuous look. Combine the curve with a filled area and you get a spline area chart.
When should you use a spline chart?
Choose a spline chart when your data change smoothly over time, and you want to reflect that gentle flow in the visual. Examples are average temperatures or rolling sales figures. The curved line is also more visually appealing than sharp angles. So it works well in presentations or dashboards where design matters as much as the message.
When you shouldn’t use a spline chart
Avoid a spline chart when precise inflection points matter, because the curve can hide sharp jumps. If data moves in abrupt steps or you need readers to see each exact point, use a standard line chart instead. Also, skip the spline if you only have a few data points. The smoothing can create misleading dips or peaks between them.
Step line chart
Alternative names: Step chart, Stepped line graph
What is a step line chart?
The step line chart only uses horizontal and vertical lines to connect the data points. It is convenient to use when you want to highlight the exact moment in time when the data changes.
When should you use a step line chart?
Use it when your data shifts at irregular moments and you want to show exactly when each change happens. Typical cases are price updates or inventory restocks.
When you shouldn’t use a step line chart
Skip a step line chart if the data changes at regular intervals or almost every time point. In that case, a standard line chart will show the pattern with less visual clutter.
Candlestick chart
Alternative name: Japanese candlestick chart
What is a candlestick chart?
A candlestick chart plots price action over time. Each “candle” has a thick body that marks the opening and closing prices and thin wicks that show the highest and lowest prices for that period. Bodies can be colour‑coded to see instantly which periods fell and which rose. Typically, they are colored red when the price closes lower than it opened and green when it closes higher.
When should you use a candlestick chart?
Use a candlestick chart for financial data when you need to see intraday or period‑by‑period price moves and spot patterns that hint at future trends. Traders and analysts rely on it for stocks, forex, and cryptocurrency because it shows volatility and market sentiment at a glance.
When you shouldn’t use a candlestick chart
Avoid a candlestick chart if you only need a single closing price per period or if your audience is not familiar with trading visuals. The extra detail can distract beginners. For basic end‑of‑day prices, a simple line or bar chart is clearer.
If you’re interested in designing a candlestick chart and adding it to your financial report, it’s possible to create it with Datylon for Illustrator.
You can read more about creating a candlestick chart in our article.
Gantt chart
What is a Gantt chart?
A Gantt chart is a bar chart that maps tasks against time. The y‑axis lists activities or tasks, and each task is drawn as a horizontal bar whose left end marks the start date and whose right end marks the finish date. The x‑axis shows the calendar, so you can see instantly when each task begins, how long it lasts, and where tasks overlap.
When should you use a Gannt chart?
Use a Gantt chart to plan or track work that unfolds over time. It is a staple in project management for monitoring schedules, deadlines, and progress, but the format suits any data that describes time blocks. You can plot crop seasons, service availability, or animal migration periods with the same layout. Any situation where “what happens when” is the key question is a good fit.
When you shouldn’t use a Gannt chart
Skip a Gantt chart if the horizontal axis is not time. When the bars represent values instead of dates, use a range bar chart instead. Also, avoid a Gantt if you need to compare the exact duration of tasks; a simple bar chart that shows length alone will make those comparisons clearer.
Barcode chart
What is a barcode chart?
A barcode chart lays very thin bars along a single axis to show the distribution of many observations. Each bar marks one data point. You can keep all bars the same thickness or vary the thickness and colour to encode extra information. The result looks like the stripes of a product barcode.
When should you use a barcode chart?
Use a barcode chart when you have many observations on one long scale but little space to show them. It works well as a compact alternative to a strip plot when the data marks would otherwise overlap. You can thicken some bars or colour them differently to highlight special states, such as events of interest or different categories.
When you shouldn’t use a barcode chart
Avoid a barcode chart if readers must see exact values or compare precise differences. The thin bars give only position, not magnitude. It is also not suitable when you need many colour classes, because thin stripes make the colours hard to distinguish.
OHLC chart
What is an OHLC chart?
An Open-High-Low-Close (OHLC) chart plots price action along a time axis. For each period, it draws a vertical line from the low to the high price, then adds two short horizontal ticks. The tick on the left marks the opening price, and the tick on the right marks the closing price. Often, the symbol is coloured green when the close is above the open and red when it is below. This way, you can see rising and falling periods instantly.
When should you use an OHLC chart?
Use an OHLC (Open‑High‑Low‑Close) chart when you need a compact view of all four key prices in each trading interval. It is a staple in finance for analysing stocks, forex, and other markets because it shows volatility and direction without the filled bodies of candlesticks, making dense timelines easier to read.
When you shouldn’t use an OHLC chart
Skip an OHLC chart if your audience only needs closing prices or if they are unfamiliar with trading visuals. In those cases, a simple line chart or bar chart of closing prices will be clearer. If the focus is on pattern recognition and you want the visual weight of filled candles, a candlestick chart may be a better choice.
That’s it for data over time charts. In the next part we’ll explore distribution charts. Take care and see you soon!
You can also check all other parts here:
Part 1: Comparison charts
Part 2: Correlation charts
Part 3: Part-to-whole charts
Part 5: Distribution charts
Part 6: Geospatial and other charts
