What does one checkmark mean in WhatsApp when sending an SMS - briefly?
When you send a message on WhatsApp and see one checkmark, it indicates that your message has been successfully sent from your device but has not yet been delivered to the recipient's phone.
What does one checkmark mean in WhatsApp when sending an SMS - in detail?
In WhatsApp, the presence of a single checkmark next to a message you've sent indicates that your message has been successfully forwarded from your device to WhatsApp's servers. This initial checkmark does not provide information about whether the recipient has received or read the message; it merely confirms that the transmission process from your end has been completed.
To break down this process in detail: when you send a message on WhatsApp, your device first encrypts the content and then forwards it to WhatsApp's servers. The appearance of the single checkmark signifies that this initial stage—the sending of the message from your device—has been accomplished successfully.
However, this is only the first step in the journey of your message. After reaching WhatsApp's servers, the message needs to be delivered to the recipient's device and then acknowledged by their device for a second checkmark to appear. Only when the recipient's device confirms receipt will you see two checkmarks next to your sent message.
In summary, the single checkmark in WhatsApp signifies that your message has left your device and is on its way to the recipient via WhatsApp's servers, but it does not guarantee delivery or reading by the intended recipient.