Explanation

Data Validation improves data accuracy by restricting the type of information users can enter.

Open:

Data → Data Validation

Main Validation Types

Validation	Example
Whole Number	Marks 0–100
Decimal	Discount 0–0.50
List	Department
Date	Joining Date
Time	Office Time
Text Length	10-digit code
Custom	Formula-based condition

Example 1 — Marks Validation

Allow only marks from 0 to 100.

Settings:

Allow: Whole Number
Data: Between
Minimum: 0
Maximum: 100

Example 2 — Drop-down List

Create this source list:

Department
Sales
HR
IT
Finance

Select the entry cells and choose:

Data Validation → List

Select the source range.

Users can then choose a department from a drop-down list.

Input Message

An Input Message can guide users about what should be entered.

Example:

Enter marks between 0 and 100.

Error Alert

An Error Alert can warn or stop users when invalid data is entered.

Practice

Create an Employee Entry Form:

Employee	Age	Department	Joining Date	Status

Apply:

• Age validation
• Department drop-down
• Date validation
• Status drop-down