what is Promotional and Feature graphic in Android Market/Play Store?

Question

What does it mean and need whether we are uploading our app into the market? Please Explain or give me a related links.

Answer 1

Promo graphic

The promo graphic is used for promotions on older versions of the Android OS (earlier than 4.0). This image is not required to submit an update for your Store Listing.

Requirements

• JPG or 24-bit PNG (no alpha)
• Dimensions: 180px by 120px

https://support.google.com/googleplay/android-developer/answer/1078870