What is Positive testing and Negative testing?

Positive testing is testing with valid data and checking if the outcome/behavior is same as expected.

Example: If a text field is supposed to accept only characters, we enter different sets of characters and see the result to check if the behavior is expected. It is positive testing.

Negative Testing is testing with invalid data and check if the application is not accepting the invalid data.

Example: If a text field is supposed to accept only characters, we enter different sets of numbers and special characters to see the result. It should not accept the invalid data. We expect an error message and if error message is appeared, it passed the testing.