The Telegram Bot API supports basic formatting for messages. You can use bold, italic, underlined and strikethrough text, as well as inline links and pre-formatted code in your bots' messages.
You can use either markdown-style or HTML-style formatting.
Markdown-style:
To use this mode, pass MarkdownV2 in the parse_mode field.
https://api.telegram.org/bot1328912345:BBCCDDExVAKD2GOEA1mXWfXfhQ_z8Y6rRh8/sendmessage?chat_id=12345678&text=Sample message&parse_mode=MarkdownV2)
Use the following syntax in your message:
*bold \*text*
_italic \*text_
__underline__
~strikethrough~
*bold _italic bold ~italic bold strikethrough~ __underline italic bold___ bold*
[inline URL](http://www.example.com/)
[inline mention of a user](tg://user?id=123456789)
`inline fixed-width code`
```
pre-formatted fixed-width code block
```
```python
pre-formatted fixed-width code block written in the Python programming language
```
HTML-style:
To use this mode, pass HTML in the parse_mode field like example below:
https://api.telegram.org/bot1328912345:BBCCDDExVAKD2GOEA1mXWfXfhQ_z8Y6rRh8/sendmessage?chat_id=12345678&text=Sample message&parse_mode=html)
The following tags are currently supported:
b>bold</b>, <strong>bold</strong>
<i>italic</i>, <em>italic</em>
<u>underline</u>, <ins>underline</ins>
<s>strikethrough</s>, <strike>strikethrough</strike>, <del>strikethrough</del>
<b>bold <i>italic bold <s>italic bold strikethrough</s> <u>underline italic bold</u></i> bold</b>
<a href="http://www.example.com/">inline URL</a>
<a href="tg://user?id=123456789">inline mention of a user</a>
<code>inline fixed-width code</code>
<pre>pre-formatted fixed-width code block</pre>
<pre><code class="language-python">pre-formatted fixed-width code block written in the Python programming language</code></pre>
Source : https://core.telegram.org/bots/api#formatting-options