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Note

Experiment keys are unique within an Optimizely project, and variation keys are unique within an experiment. However, experiment keys and variation keys are not guaranteed to be _universally _unique because they are user-generated. This may become a problem in your analytics reports if you use the same key in multiple Optimizely projects or rename your keys.

For human-friendly strings when absolute uniqueness is not required, use keys. If you need to uniquely identify experiments and variations in a way that will not change when you rename keys, use the automatically generated IDs.

## Android

Keys can be accessed on `Experiment` and `Variation` objects using `getKey()`, and IDs can be accessed using `getId()`.

## Java

Keys can be accessed on `Experiment` and `Variation` objects using `getKey()`, and IDs can be accessed using `getId()`.

## Objective-C

Keys and IDs can be accessed on `OPTLYExperiment` objects using `experimentKey` and `experimentId` respectively. Likewise, keys and IDs can be accessed on `OPTLYVariation` objects using `variationKey` and `variationId`.

## Swift

Keys and IDs can be accessed on `OPTLYExperiment` objects using `experimentKey` and `experimentId` respectively. Likewise, keys and IDs can be accessed on `OPTLYVariation` objects using `variationKey` and `variationId`.