What is purpose of with keyword when using relationships of eloquent in Laravel?

Article Model

class Articles extends Model
{
    protected $fillable = ['id','title', 'body', 'students_id', 'created_at', 'updated_at'];
    protected $table = 'articles';

    public function students(){
        return $this->belongsTo('App\Students');
    }

    public function categories(){
        return $this->belongsTo('App\Categories');
    }
}

Code 01 : $articles = Articles::with('students')->with('categories')->get();

Code 02 : $articles = Articles::get();

Whatever code(01 or 02) I used I got the object which join article,categories and students tables.

So my question is what is the purpose of with('students')->with('categories') part?

via Chebli Mohamed