I think there’s a couple different questions getting bunched together here, maybe?
Markup and Markdown
When you want text that can be bolded, italicized, etc., the programming jargon term for that is “rich text” (as opposed to “plaintext” without any formatting). “Hypertext” – as in “hypertext markup language” (HTML) – is similar, basically rich text + the ability to link to other documents.
HTML is what powers the web, with code like <strong>this is a bold <a href="example.com/blah">link</a></strong>
. But that’s kinda hassle to write, right? Which is how we got BBcode like [b]this is a bold [url="example.com/blah]link[/url][/b]
. Microsoft Word has its own markup language (a dialect of XML), LibreOffice does too, etc.
But that’s all needlessly complicated. What if you just want a simple way to do basic formatting plus links? That’s the whole idea behind Markdown, replacing overly-complicated markup with simple marks like **this is a bold [link](example.com/blah)**
. There, same effect, but much shorter, and easier for humans to write.
That’s all it is. There are various dialects of Markdown, as @LSLGuy mentioned, but that’s really just a technical implementation detail that you don’t really need to worry about unless you’re a programmer.
These days, especially, there are many editors (not just Obsidian, but also Google Docs, Macdown, and a bunch of others) that let you make simple Markdown files without the hand-coding. You just click bold/italic/link/etc. like you would in Word, and it automatically generates the Markdown for you. You can see a simple online one here, with a side-by-side code view and “what you see is what you get (wysiwyg)” view.: Free Online Markdown Editor | WYSIWYG GFM Editor | JekyllPad
WYSIWYG is an old 90s/2000s term for “software that shows you a live preview of your actual output, as you’re typing, rather than making you wonder if your code is right”. These days it’s kind of an obsolete term because most consumer software is WYSIWYG by default.
Different kinds of editors
Editing text can be done by all sorts of different software, but they have different specializations.
Word, LibreOffice, etc. are word processors. They focus on layout, typography, etc. Sure, you can use them to take notes too, but it’s overkill.
Text editors are kind of the opposite of that spectrum. They are good for editing plaintext, but don’t always make formatting easy. Importantly, they usually don’t include any sort of built-in organization, autosave, linking, etc… that’s all up to you to handle, using filenames and folders etc.
In between them are “shitty wannabe word processors” like Wordpad, TextEdit, etc. They’re not really good at anything, and should be avoided entirely, lol. But people historically used them for notes when they didn’t want to deal with the complexity of a full-blown word processor, yet needed something more than a text editor.
But these days, an entire category of note-taking apps exists. Not just Obsidian, but also OneNote, Evernote, Goodnotes, or at the company/enterprise level, things like Clickup, Notion, etc… They can handle basic formatting and linking, but importantly, they also help you organize your notes and keep track of them, and takes care of mundane things like auto-saving, cloud backups, etc. (sometimes) so you don’t accidentally lose thoughts.
Obsidian is just one of those many note-taking apps. Its speciality is in using Markdown, which keeps your notes as simple standard text files on your computer (meaning no database or cloud server needed, and you can easily copy those to a USB drive or whatever). Markdown, being relatively standard, is easily opened and edited by other software too. So there’s a very good chance the notes you write today will still be openable in 20 years.
But if that doesn’t really matter to you, software like OneNote might offer you similar note-taking and organization capabilities, but also automatically take care of cross-device syncing (you can view all your notes on your laptop, phone, desktop, web browser, whatever), as well as easily add drawings, diagrams, math formulas, etc. It’s a great tool for school/college.
All this software all have subtly different features, strengths, and weaknesses. But they focus on making the note-taking experiencing easier, as opposed to document layout and desktop publishing. If want to organize a jumble of thoughts, these tools will work better. If you want to make a nice-looking flyer, they’re probably not the right tool.