KakaoTalk ID is an identification username used in place of a phone number. Users can easily search and add friends by KakaoTalk IDs instead of by phone number.  

From the Friends tab, long-tap the person you wish to block and select Block.

To block a person on the Recommended Friends list, long-tap the person you wish to block or tap Block on their mini-profile.

If you want to unblock someone, go to the Friends tab, tap the gear-shaped icon on the top-right corner and select Blocked Friends.

Go to the Find tab (the magnifying glass icon) and tap the Edit button on the top-right corner to edit your friends list.

The deleted users will be permanently removed from your recommended friends list.

KakaoTalk allows you to add close friends to your Favorites list. To add a friend to Favorites, tap the star icon on your friend's mini-profile. To remove a friend from Favorites, deselect the star icon. 

In a chatroom, tap the triple-lined menu on the top-right corner, tap "+ Invite” and select a friend.  

Tap the profile picture of the person to open the mini-profile and select Add Friend. 

OR - In the chatroom, tap the triple-lined menu on the top-right corner and you will see the participants in your chat. A question mark will appear on the profile picture of any participant who is not on your friends list. Tap the silhouette button to add the user to your friends list. 

This number indicates the number of friends who have not yet read a message. The number will disappear when all of your friends have checked the message. 

To save chats from a chatroom, and tap the on the top-right corner of the chatroom. 

Then tap the gear-shaped icon on the bottom and select [Export Messages]. 

You can choose from [Send Text Only] or [Save All Messages to Internal Storage].