I recently worked on an Optimizely project where the customer wanted to serve gated content to visitors. If you're not familiar with gated content, it's where content is only available to a user that fills out a form - the form being the "gate". Gated content can be a powerful marketing tool to help capture valuable information for lead generation, or for tracking visitor statistics.
In our case, the customer wanted to provide whitepaper downloads to visitors that provided a defined set of information. Our goal was to create this interaction using Optimizely Forms.