## What Does It Do?
**WebJack is a wired, bidirectional data link between the Arduino Uno and your phone, established via headphone jack.** It uses two distinct frequencies for a modem-like serial transmission of data. WebJacks runs in the browser and its goal is to provide a way to read sensors without the burden to install native applications. Look for recent updates on Public Lab [here](http://publiclab.org/tag/webjack).
This is a list of community-generated guides for specific applications and the development of WebJack. These [activities can be categorized](https://publiclab.org/wiki/activity-categories), and some may be more reproduced -- or reproducible -- than others. Try them out to build your skills, and help improve them by leaving comments. Together, we can repeat and refine the activities into experiments.
### Activity grid
## Frequently Asked Questions
<a class="btn btn-primary" href="/post?tags=question:webjack&template=question">Ask a question about WebJack</a>
* data as text
* binary data
* Firmata RPC messages
We're working to refine and improve WebJack on a number of fronts; here, take a look at the leading challenges we're hoping to solve, and post your own.
Be sure to add:
* constraints: expense, complexity
* goals: performance, use cases
## Build a data link with WebJack
Instructions on the circuit and software needed for WebJack can be found here:
### Demo WebJack applications
- [Using Firmata with WebJack as transport](https://publiclab.github.io/webjack-firmata/example):
<iframe width="560" height="315" src="https://www.youtube.com/embed/eWr3kahwo78" frameborder="0" allowfullscreen></iframe>
- [WebJack demo website](https://publiclab.github.io/webjack/examples)
- For more information about WebJack, post a question to the "dev" mailing list [here](https://groups.google.com/group/plots-dev)) (also listed in the left sidebar)
- The github repo of WebJack is [here](https://github.com/publiclab/webjack)