Somebody needs to house your posts and themes and plugins and connect them to the internet. Your domain name is an address. Like the number on your street that tells people where you live.
You're basically asking... "Ok so I've been building this furniture and got a bunch of rugs and a bed. Do I need a house to put them in? It would be cheaper if I just drop them at my address and sleep there. Do I need a house?"
Yes. You need hosting. The question is, do you need someone else to host it for you? Do you know how to set up a local server and connect it to the internet so that Google's bots can crawl it and you can mess around with SEO?
If you can build your own house, you don't need to rent someone else's.
Or get a tent.
There are very cheap hosting options out there. Also free domain options. So if you're interested in digging around you don't have to splash the cash to learn how search engines work. You can get a trial from some people for $1. There's hosting at $3/month. It's not good hosting, mind you, so you'd probably need to move in someone else's house if you want to actually have people visit regularly, but it's good enough for your work to sleep in and for Google's spiders to build their webs in it.
But, honestly... this is really basic stuff. It should take you 5-10 minutes to figure it out. You don't need us to tell you this, and if you're trying to learn how search engines work and how to do SEO, but you don't even know how to search whether or not you need hosting for your website...
You'd likely have an easier time if you started from there.
It's very difficult to figure out SEO if you don't know how search engines work for the end-user (e.g. you)
Go and ask them questions and see how they answer. Figure out these issues for yourself. Tell us what you learn. And we'd be way more inclined to help you out and point out if what you learned needs adjusting. Blanket questions like "How do I build a house? Do I need bricks?" aren't very helpful.
You're basically asking... "Ok so I've been building this furniture and got a bunch of rugs and a bed. Do I need a house to put them in? It would be cheaper if I just drop them at my address and sleep there. Do I need a house?"
Yes. You need hosting. The question is, do you need someone else to host it for you? Do you know how to set up a local server and connect it to the internet so that Google's bots can crawl it and you can mess around with SEO?
If you can build your own house, you don't need to rent someone else's.
Or get a tent.
There are very cheap hosting options out there. Also free domain options. So if you're interested in digging around you don't have to splash the cash to learn how search engines work. You can get a trial from some people for $1. There's hosting at $3/month. It's not good hosting, mind you, so you'd probably need to move in someone else's house if you want to actually have people visit regularly, but it's good enough for your work to sleep in and for Google's spiders to build their webs in it.
But, honestly... this is really basic stuff. It should take you 5-10 minutes to figure it out. You don't need us to tell you this, and if you're trying to learn how search engines work and how to do SEO, but you don't even know how to search whether or not you need hosting for your website...
You'd likely have an easier time if you started from there.
It's very difficult to figure out SEO if you don't know how search engines work for the end-user (e.g. you)
Go and ask them questions and see how they answer. Figure out these issues for yourself. Tell us what you learn. And we'd be way more inclined to help you out and point out if what you learned needs adjusting. Blanket questions like "How do I build a house? Do I need bricks?" aren't very helpful.