Are you bored of using the same old simple plain text is your Whatsapp messages? If yes, then you could try formatting your messages. Whatsapp allows you italicize, bold, strikethrough, monospace, and underline text in your messages.
There are two ways to format your text. One way is to add a symbol to either side of the word you wish to format and the other is to select the text and choose from the options given.
To italicize your message, place an underscore on both sides of the text: _text_
To bold your message, place an asterisk on both sides of the text: *text*
To strikethrough your message, place a tilde on both sides of the text: ~text~
To monospace your message, place three backticks on both sides of the text:“`text“`
Alternatively on Android, you can tap and hold the text you are typing > More > and choose among bold, italic, strikethrough and monospace.
On iPhone, you can tap and hold the text you are typing > BIU > and choose among bold, italic and strikethrough.
WhatsApp uses underline text for website links, dates, and other texts by default. As of now you can not underline the text yourself in WhatsApp but in future there is hope that WhatsApp will add the feature as it it being requested by many users.