Some export backends include commands to convert a region of Org formatted text to another format, such as HTML or LaTeX. The conversion replaces the original source. Here are such commands:
org-export-region-to-ascii ¶Convert the selected region into ASCII.
org-export-region-to-utf8 ¶Convert the selected region into UTF-8.
org-export-region-to-html ¶Convert the selected region into HTML.
org-export-region-to-latex ¶Convert the selected region into LaTeX.
org-export-region-to-texinfo ¶Convert the selected region into Texinfo.
org-export-region-to-md ¶Convert the selected region into Markdown.
The in-place conversion is particularly handy for quick conversion of tables and lists in non-Org buffers. For example, in an HTML buffer, write a list in Org syntax, select it, and convert it to HTML with M-x org-html-convert-region-to-html.