| Descriptor | Set of unique features received from the sample. It is used for matching of faces. Descriptor is not considered personal data. | 
| Index | LUNA Index Module (LIM) entity containing set of received from user-provided images and deployed together for approximate matching. The index is generated by the Indexer service after receiving the task from the Index Manager service. | 
| Matching | The process of comparing descriptor with some descriptor batch that results in similarity scores. Its purpose is to search most similar descriptors to a given one over some user-provided set of descriptors. | 
| Matching label | LIM entity that contains the ID of a list of faces. | 
| Relevant index | Last built index for the list, since the index can be rebuilt if the task is created automatically. | 
| Sample | Image containing a face and corresponding to VisionLabs and other standards. |