High-level Overview

An Anchor program consists of three parts. The program module, the Accounts structs which are marked with #[derive(Accounts)], and the declare_id macro. The program module is where you write your business logic. The Accounts structs is where you validate accounts. Thedeclare_id macro creates an ID field that stores the address of your program. Anchor uses this hardcoded ID for security checks and it also allows other crates to access your program's address.

When you start up a new Anchor project, you'll see the following:

// use this import to gain access to common anchor features
use anchor_lang::prelude::*;


// declare an id for your program
declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");


// write your business logic here
#[program]
mod hello_anchor {
    use super::*;
    pub fn initialize(_ctx: Context<Initialize>) -> Result<()> {
        Ok(())
    }
}


// validate incoming accounts here
#[derive(Accounts)]
pub struct Initialize {}

We'll go into more detail in the next sections but for now, note that the way an endpoint is connected to its corresponding Accounts struct is the ctx argument in the endpoint. The argument is of type Context which is generic over an Accounts struct, i.e. this is where you put the name of your account validation struct. In this example, it's Initialize.