Field Explorer: The Field Explorer, which is part of the embedded Crystal Reports Designer, shows a tree view of Database Fields and Special Fields that are available for you to add to your report. The Field Explorer also shows the Formula, Parameter, Group Name, Running Total, SQL Expression, and Unbound Fields that you have defined for use in your report.
There are various fields are available in field explorer of the Crystal Report are as follows:
Database Fields: A database is designed to store related data. Each database record is made up of one or more database fields. Each database field can hold one piece of data.
Formula Fields: A formula is an equation designed to produce specific data for your report. You can use formulas to perform many calculations, including the calculation of numeric values and the comparison of multiple values etc.
Page Header: Appears after the Report Header on the first page and on all the
remaining pages it appears at the top of the page.
Page Footer: Appears at the bottom of each page.
Details: The row that displays the record information. There is usually one detail
row for every record in the table.
Report Header: Appears at the top of the first page of the report.
Report Footer: Appears as the bottom of the page for the last page in the report.