when using line graphs to track the price of a stock the data point most commonly used is the closing price of the stock 
for example assume that on day one of trading a given stock s price was 30 resulting in a data point at 1 30 on day two of trading the stock s price was 35 resulting in a data point at 2 35 each data point is plotted and connected by a line that visually shows the changes in the values over time if the value of the stock increased daily the line would slope upward and to the right conversely if the price of the stock was steadily decreasing then the line would slope downward and to the right types of line graphsthere are three main types of line graphs although each type is fundamentally rooted in the same principles each has its own unique situation where it is best to implement and use a simple line graph is the most basic type of line graph in this graph only one dependent variable is tracked so there is only a single line connecting all data points on the graph all points on the graph relate to the same item and the only purpose of the graph is to track the changes of that variable over time this graph cannot be used to compare the variable to another variable because only variable is charted in the example below the x axis is time and the y axis is the year over year change in price for all consumer goods in the united states this graph of the consumer price index shows the annual rate of inflation and since it is analyzing just one set of data all items there is only one line bureau of labor statisticsin a multiple line graph more than one dependent variable is charted on the graph and compared over a single independent variable often time different dependent variables are often given different colored lines to distinguish between each data set each line relates to only the points in its given data set lines do not cross between dependent variables for example the line graph below shows the consumer price index again however this graph shows the change in price for three different categories medical care red commodities green and shelter blue in this graph we can see the growth in price for commodities was higher than the other two categories in july 2022 however shelter or medical expenses were typically the groups that experienced higher inflation over the past decade 1bureau of labor statisticsa compound line graph uses multiple variables similar to a multiple line graph however the variables are often stacked on top of each other to show the total quantity across all variables this not only informs users of the relationship between each of the variables but it informs of how the total changes as well in the example below from the environmental protection agency epa there are five dependent variables that range from abnormally dry land areas to exceptional drought areas the most extreme drought data was graphed first and any empty space under that line graph was shaded dark red then subsequent sets of data were plotted after with the empty area below each of those lines shaded their respective colors in total this shows the relationship between drought descriptions as well as the total percent of u s land area in these categories by year epaparts of a line graphline graphs may vary depending optional features or formatting the highest quality easiest to understand line graphs have the following characteristics line graphs may have a title above the graph to succinctly explain what the graph is depicting unless you provide a user with written context the user will often rely on the title to better understand what data is being pulled in the title may specifically call out a timeframe or limits to the data i e an appropriate title for the compound line graph could be level of u s dry land by year 2000 2015 the legend explains what each dependent variable is and how to distinguish different sets of data in the example above each dependent variable is marked with its own color the box that explains what each color means is the legend each item of data on a line graph is a reference to a different source that ties the dependent variable to an independent variable this is the information on your graph it is the item that creates the dots that get connected to form the lines on your chart in some examples as seen above there may be multiple sets of data combined into a single graph to ensure data is protected and accurate companies may have specific data integrity analyst or similar positions to monitor database activity the x axis is the set of information that runs along the horizontal flat portion at the bottom of the line graph in most line graphs the x axis will be related to time whether it is the different months in a year or the number of weeks that have passed since a product launch the y axis is the set of information that runs along the vertical left side of the graph some iterations of line graphs have this set of information on the right in any case these numbers count the items being measured the graph may start at zero though there are instances where it makes more sense to start at a higher number last we have the line the line connects all data points within a single dependent variable this line s movement shows the increase and decrease of information across time it can also easily be compared against other lines as long as all data sets are being measured over similar periods of time though overly simplified this line can communicate to management what actions should be taken to improve operations or strategic planning want to display multiple sets of data but one set of information is more suitable as a bar chart programs such as excel and google sheets can produce combined charts where one dependent variable is shown as a bar graph and another dependent variable is shown as an overlying line graph creating a line graph in excelyou can use a line graph in excel to display trends over time in excel line graphs are appropriate if you have text labels dates or a few numeric labels on the horizontal axis x axis here are the steps to create a line graph in excel if you are using numeric labels empty cell a1 before you create the line graph uses of a line graphdifferent data visualization tools are best used for specific purposes and a line graph is no exception depending on the underlying data a line graph is best for 