## In the beginning there was Vert.x

You can’t do much in Vert.x-land unless you can communicate with a `Vertx` object!

It’s the control centre of Vert.x and is how you do pretty much everything, including creating clients and servers, getting a reference to the event bus, setting timers, as well as many other things.

So how do you get an instance?

When you start your application with the CLI, a `vertx` variable will be made available to your code.

    var server = vertx.createHttpServer(); // (1)
    server.requestHandler(function (request) {
     request.response().end("Hello world");
    });
    server.listen(8080);

1. At runtime, `vertx` variable is available

Then run the applicaton with the CLI:

    vertx run my-verticle.js

Note | Most applications will only need a single Vert.x instance, but it’s possible to create multiple Vert.x instances if you require, for example, isolation between the event bus or different groups of servers and clients.

### Specifying options when creating a Vertx object

When creating a Vert.x object you can also specify options if the defaults aren’t right for you.

    vertx run my-verticle.js -options my-options.json

If you want to increase the worker pool size, your `my-options.json` file may look like:

    {
     "workerPoolSize": 40
    }

The `VertxOptions` object has many settings and allows you to configure things like clustering, high availability, pool sizes and various other settings.

### Creating a clustered Vert.x object

If you’re creating a clustered Vert.x (See the section on the event bus for more information on clustering the event bus), add the `-cluster` option:

    vertx run my-verticle.js -cluster