Does using my MacBook Air while plugged in affect the battery?

The accepted rule of thumb is to plug in to power when that is available and run on the battery when you must.

The best advice for getting the most from your battery:

• Plug in when using the computer near available power.

• Use on battery when ac is unavailable.

• Don’t subject the computer and battery to extreme temperatures.

• Let the OS and charging circuits manage the charging.

• Try not to allow the battery to discharge deeply regularly before plugging in. Yes, it may happen from time to time, just don't make it a habit.

• Don't obsess over battery life and/or health.  

Here is Apple's guidance on the subject.

Batteries - Maximizing Performance - Apple Support

About battery health management in Mac laptops - Apple Support

abhiram1o1 wrote:

should I be using my Mac plugged in or use it on the battery after charging it. will it damage the battery when I use it plugged in!

Plug in the computer whenever convenient to do so. Leaving the computer plugged in will not damage the computer or the battery. The MacOS manages the power/charging system very well. There is no need for you to try to micromanage the system.

There was a time when there were certain best practices for long battery life but today thanks to improved battery technology and Apple’s smart charging software we really don’t need to worry about it. My habit for the last 10 years has been to keep it plugged in when I have access to an electric outlet. The one thing I do try hard to avoid is to run the battery down to 0.

It shouldn't damage it to use it while plugged in but i would just use the battery and charge when you need to.