A
chart is a graphical representation of data, in which "the data is
represented by symbols, such as bars in a bar chart, lines in a line
chart, or slices in a pie chart". A chart can represent tabular numeric
data, functions or some kinds of qualitative structures.
Charts are
often used to ease understanding of large quantities of data and the
relationships between parts of the data. Charts can usually be read more
quickly than the raw data that they are produced from.Certain types of
charts are more useful for presenting a given data set than others. For
example, data that presents percentages in different groups (such as
"satisfied, not satisfied, unsure") are often displayed in a pie chart,
but may be more easily understood when presented in a horizontal bar
chart. On the other hand, data that represents numbers that change over a
period of time (such as "annual revenue from 1990 to 2000") might be
best shown as a line chart.