What Internet protocol is used by android play store app?

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I know this is not programming question but i really want to know what internet protocol is used by google play store, as of know i am thinking they are using HTTPS but i am not sure about whether they used it for searching or downloading, i searched but not find satisfactory answer.

I also how i will protocol used by different apps installed in android.

I tried to find different protocol used by different application and i sort of find about some apps like Whatsapp, FB etc but i need to find about mostly used protocol.

This information is need for my literature survey for my research.