Here's how to know if someone read your text on Android and iOS smartphones. This article also covers WhatsApp, Facebook Messenger and Instagram.
How to Check If Someone Read Your Text Message
On iPhone, read receipts are the only way to see if someone has read a text you’ve sent in Messages, the default texting app for iOS. If you and your recipient enable read receipts, the word Read will appear beneath the most recent message, along with the time the message was read.
Here's how to turn read receipts on or off in Messages for iOS:
Turn on 'Send Read Receipts'.