Summarize this article in one sentence.
You can open it in your internet browser at https://www.facebook.com or use a mobile app. You can create a new post from the top of your News Feed, or click any text field, such as a comment box. This will create the standard, red heart emoji when you post your text. This will open the available emoji library.  If you're in a desktop browser, click the smiling face icon in the lower-right corner of the text box. If you're using the mobile app, tap the emoji icon at the bottom corner of your keyboard. This will add the selected heart icon to your post.  You can also copy and paste a pre-typed heart, such as: Beating Heart: 💓 Broken Heart: 💔 Sparkling Heart: 💖 Growing Heart: 💗 Heart with Arrow: 💘 Blue Heart: 💙 Green Heart: 💚 Yellow Heart: 💛 Red Heart: ❤️ Purple Heart: 💜 Heart with Ribbon: 💝

Summary:
Open Facebook on your computer, phone or tablet. Click or tap the text field you want to edit. Type <3 into the text field. Click or tap the emoji icon. Find and select the heart emoji you want to type.