Select the range of data
Go to the Home tab
Click Conditional Formatting
Choose Highlight Cells Rules
Select Duplicate Values
Pick a formatting style
Click OK
Use Remove Duplicates from the Data tab to delete duplicate records
Select the columns to check for duplicates
Click OK to remove duplicate entries
Use COUNTIF to identify duplicates with a formula
Enter a formula such as =COUNTIF($A$2:$A$100,A2)>1
Copy the formula down the column
Filter the results to show duplicate records
Use PivotTables to summarize repeated values
Sort the data to group duplicate records together