A CI/CD Pipeline is a series of steps that must be performed in order to deliver a new version of software. A pipeline typically includes stages for:

1. Building the code
2. Running automated tests
3. Deploying to staging/production environments

Example of a basic Jenkins Pipeline:
```groovy
pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                sh 'npm install'
                sh 'npm run build'
            }
        }
        stage('Test') {
            steps {
                sh 'npm run test'
            }
        }
        stage('Deploy') {
            steps {
                sh './deploy.sh'
            }
        }
    }
}
```

Jenkins is an open-source automation server that helps automate parts of software development related to building, testing, and deploying, facilitating continuous integration and continuous delivery (CI/CD).

Key features include:
- Easy installation and configuration
- Hundreds of plugins available
- Built-in GUI tool for easy updates
- Supports distributed builds with master-slave architecture
- Extensible with a huge number of plugins