# Using AWS Elemental MediaTailor to insert ads
A configuration is an object that you interact with in AWS Elemental MediaTailor. The configuration holds the mapping information for the origin server and the ad decision server (ADS). You can also define a default playback for MediaTailor to use when an ad isn't available or doesn't fill the entire ad avail.
If you use a content delivery network (CDN) with MediaTailor, you must set up the behavior rules in the CDN before you add CDN information to the configuration. For more information about setting up your CDN, see [Using a CDN to optimize MediaTailor ad personalization and content delivery](integrating-cdn.md).
**Topics**
+ [Supported audio and video codecs](#supportedcodecs)
+ [Understanding AWS Elemental MediaTailor ad insertion behavior](ad-behavior.md)
+ [MediaTailor server-guided ad insertion overview and implementation](server-guided.md)
+ [MediaTailor ad server integration requirements](vast.md)
+ [MediaTailor playback configuration management](working-with-configurations.md)
+ [Integrating a content source for MediaTailor ad insertion](integrating-origin.md)
+ [Integrating AWS Elemental MediaTailor with Google Ad Manager](gam-integration.md)
+ [Customizing ad break behavior with ad break suppression](ad-rules.md)
+ [MediaTailor bumper ad insertion](bumpers.md)
+ [MediaTailor pre-roll ad insertion](ad-behavior-preroll.md)
+ [MediaTailor slate ad insertion](slate-management.md)
+ [Prefetching ads](prefetching-ads.md)
+ [Using preconditioned ads with AWS Elemental MediaTailor](precondition-ads.md)
+ [MediaTailor dynamic ad variables for ADS requests](variables.md)
+ [MediaTailor manifest query parameters](manifest-query-parameters.md)
+ [Reporting ad tracking data](ad-reporting.md)
+ [Overlay ads](overlay-ads.md)
+ [Ad ID decoration](ad-id-decoration.md)
## Supported audio and video codecs
MediaTailor supports the following codecs.
+ Audio codecs: mp4a, ac-3, and ec-3
+ Video codecs: h.264 (AVC), h.265 (HEVC), av01 (AV1)