Concepts / Software framework
If you don’t want to code something from scratch, if you don’t fancy staring at a blank page, then you will find yourself an appropriate software framework. Using a framework saves time, reduces the risk of errors, and assures higher reliability than otherwise.
Typically, there will a choice of frameworks. For example, the Ethereum Foundation maintains a list of decentralized app (dapp) development frameworks.
Frameworks represent structure in the sociological sense. An opinionated framework (more insistent you do things ‘its way’) may be more convenient in many contexts, but the more opinionated the framework, the more rigid the associated structure.