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> Must-knows for working with the emnify SDKs

## SDK glossary

| Name                | Description                                                                                                                                                                                                                                                 |
| :------------------ | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Device              | Any physical device supplied with a SIM that obtains connectivity. It's important not to mix up the terms 'Device' and 'Endpoint.' A device is a superset of the endpoint and SIM acting as a whole. [Learn more about devices](/quickstart/create-device). |
| Device status       | Primary way to control connectivity. It can be either **Enabled** or **Disabled**. When **Enabled**, a device that has a SIM assigned can go online. On the other hand, when **Disabled**, the device doesn't get any service.                              |
| SIM                 | Represents a physical or eSIM issued by emnify. [Learn more about SIMs](/services/esims).                                                                                                                                                                   |
| SIM status          | Status of the SIM's phase in the [SIM lifecycle](/services/sim-lifecycle-management). When using the SDK, avoid changing the SIM status directly. Instead, change it using the device status.                                                               |
| Tariff profile      | Controls where and how your devices have coverage. Referred to as **coverage policies** in the emnify Portal. [Learn more about tariff profiles](/developers/reference/tariff-profile).                                                                     |
| Service profile     | Defines available services (for example, SMS, 4G, etc.) and usage for a device. Referred to as a **service policy** in the Portal. [Learn more about service profiles](/developers/reference/service-profile).                                              |
| Blocklist operators | Method that allows you to restrict device connectivity to a specific operator or group of operators. Referred to as **networks blocklist** in the Portal.                                                                                                   |
| Operator            | Underlying mobile network operator (MNO) used to provide connectivity. Referred to as a **network** in the Portal. Explore network coverage by country and region on emnify's [pricing page](https://www.emnify.com/plans-and-packages).                    |
| SMS                 | [Learn more about SMS](/services/sms).                                                                                                                                                                                                                      |
| Application token   | Authenticates your identity when using the emnify SDK and API. [Learn how to generate an application token](/developers/auth/application-tokens).                                                                                                           |

> **Tip**
>
> More terminology and definitions are available in the [IoT glossary](https://www.emnify.com/iot-glossary).