Android
Pin a Conversation to the Top of Messages auf Android
Google Messages sorts every conversation by the timestamp of the last message. A contact you message daily can still end up buried below one-off chats if those happen to be more recent.
Pinning removes a conversation from that automatic sorting. Once pinned, it stays anchored at the top of the list, independent of when the last message arrived.
Menu path
Open Tap on Messages ➔ Tap and hold a Conversation ➔ Tap on Pin. The conversation moves to a fixed row above the regular, time-sorted list.
You can pin more than one conversation. When multiple chats are pinned, they still sort by recency among themselves, but all of them stay above the unpinned ones.
This works for both one-on-one chats and group conversations. Archiving or muting a conversation does not affect its pinned status, but deleting the conversation removes the pin along with it.
If you need quick access to a contact without cluttering your home screen with a shortcut, pinning inside the app is the faster option since it needs no extra setup outside Messages.