Open several files in new tabs with VIM

Use the -p flag:

vim -p *.c

The above will open all files matching *.c.

You can also create an alias for this (I have alias vip='vim -p' and I only type vip *.c for the above example)

If you want to open only .md.

vim -p *.md

Or after opening vim, use :args to specify md files.

:args *.md
:tab all

If you are in Vim, this command will open each html file in the current directory in its own tab and restore syntax support (disabled by :argdo):

:args *.html | argdo tabe | tabdo syntax on

If you are in your shell, go for the other answers.