Can you explain how the build and deployment automation process is structured in Jenkins?

Jenkins is a tool for automating build and deployment processes, which operates on a pipeline principle. The process typically includes the following steps:

1. Code retrieval — Jenkins automatically fetches source code from a version control system (e.g., Git).
2. Build — compiling and assembling the project using scripts or build tools (Maven, Gradle, etc.).
3. Testing — running automated tests to verify code quality.
4. Deployment — automatically publishing the built artifact to test or production servers.

In Jenkins, this is configured through a Jenkinsfile, which describes the sequence of steps. For example:

pipeline {
    agent any
    stages {
        stage('Checkout') {
            steps {
                git 'https://github.com/example/repo.git'
            }
        }
        stage('Build') {
            steps {
                sh './gradlew build'
            }
        }
        stage('Test') {
            steps {
                sh './gradlew test'
            }
        }
        stage('Deploy') {
            steps {
                sh './deploy.sh'
            }
        }
    }
}

Thus, Jenkins automates the entire cycle from code to deployment, reducing manual labor and errors.