It's always lovely to be generous and treat someone to an item or two without going into a trade so you can hand them straight over. Please ensure you're giving this gift out of kindness and not being forced to do so or participating in what could be a scam.
If you believe you may be involved in a gifting scam, find out what to do here.
Not all people will be open to receiving gifts, so you may find that when you attempt, you may be unsuccessful. However, here's the process of gifting someone happy to receive an item:
Click or tap on their avatar so the interaction menu appears, and then press the second option, "Give Item".
The first fail-safe for the menu will appear, checking whether you'd like to give an item from your backpack. Click "From Backpack" to continue gifting or "Back" to cancel and return.
This will bring up your backpack menu, where you can select an item to give to your friend. As a safety and security feature, you cannot gift legendary items to other players, and this can only be done through trading.
Once again, you'll encounter another security pop-up to confirm that you want to give this item away. You can use this time to double-check that you want to gift an item and that you have selected the correct item to send.
Upon selecting "Yes", that is the point of no return, and your item will be sent immediately to them. Once an item has been gifted to another player, our Support team cannot get involved in helping with its return.