STEP-1

Open the Default Browswer "Safari"

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STEP-2

You can search a  Website from here.

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STEP-3

For example i'm  using "Wikipedia"

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STEP-4

Display the Safari tab bar and tap the action button.

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STEP-5

In the share sheet, tap Add bookmark.

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STEP-6

Just click to "Save".

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STEP-7

Here you can see your Bookmarked Website.

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This is complete process of the bookmarking any of your  Favorite website on iPhone.