Pie-diagram is used for comparing different components and their relation to the total. This means that a pie chart is a circular chart that represents data in terms of the proportion of the whole. It is used to show the percentage breakdown of a set of data into its constituent parts.

Explanation:
Pie-diagram is a graphical representation of data that consists of a circle divided into sectors, each representing a proportion of the whole. The size of each sector is proportional to the quantity it represents. The pie chart is an effective way to represent data because it is easy to understand and visually appealing.

Components:
A pie chart has the following components:
- Title: It provides a brief description of the data that is being represented.
- Sectors: These are the different parts of the data that are being represented. Each sector is represented by a slice of the pie.
- Labels: These are used to identify each sector and provide additional information about it.
- Legend: It is an optional component that provides additional information about the data being represented.

Uses:
Pie charts are used to represent data in a variety of fields, including:
- Business: Pie charts are used to represent sales figures, market share, and other business-related data.
- Education: Pie charts are used to represent the percentage of students in different grades, the number of students who passed or failed a test, and other educational data.
- Science: Pie charts are used to represent data in scientific research, such as the percentage of different species in a particular ecosystem.

Advantages:
- Easy to understand
- Visually appealing
- Can be used to represent large amounts of data
- Provides a clear picture of the proportion of each component to the whole

Disadvantages:
- Can be difficult to read if there are too many sectors
- Can be misleading if the data is not represented accurately
- Cannot be used to show trends or changes over time

Conclusion:
Pie-diagrams are used for comparing different components and their relation to the total. It is an effective way to represent data in a variety of fields and provides a clear picture of the proportion of each component to the whole. However, it should be used with caution and accuracy to avoid misrepresenting data.

In pie chart the data is converted into degree measure then it shown in the pie chart. thus it relates the given data to a specific area of a circle. Therefore it compare data not to the original fact but to the total area covered in the circle in degree.