How are blockchain applications written?

Question

Hashing

Who can tell how blockchain applications are created, hosted, launched and used by users?
As I understand it, this is what they are talking about, that they say "we use blockchain" are we talking about smart contracts?
Is there any sample code that can be run by a normal user, i.e. as easy as going to the site, without installing anything?

Answer 1

bitcoin forks
https://github.com/bitcoin/bitcoin
rewrite, add functions depending on the developer's plans

Answer 2

If we are talking about Ethereum, then they write in a js-like Solidity language, for example, in Remix https://remix.ethereum.org