# Creating activities with code (legacy)

> :::important
The information on this page refers to activities that target the deprecated .NET Framework. For information about creating activities targeting .NET for the latest versions of Studio, see [Creating activities with code](https://docs.uipath.com/sdk/other/latest/developer-guide/creating-activities-with-code).
:::
An activity is the building block of a process automation. UiPath Studio comes with various built-in dedicated activities (such as PDF, mail, Excel, SAP, and more) you can install through the Package Manager, depending on your needs. You can read [The UiPath Activities Guide](https://docs.uipath.com/activities/other/latest) for more details and examples, as well as how to [Manage Activities Packages](https://docs.uipath.com/studio/docs/managing-activities-packages) . Additionally, you can create custom activities to better automate processes based on your needs.

:::important
The information on this page refers to activities that target the deprecated .NET Framework. For information about creating activities targeting .NET for the latest versions of Studio, see [Creating activities with code](https://docs.uipath.com/sdk/other/latest/developer-guide/creating-activities-with-code).
:::
An activity is the building block of a process automation. UiPath Studio comes with various built-in dedicated activities (such as PDF, mail, Excel, SAP, and more) you can install through the Package Manager, depending on your needs. You can read [The UiPath Activities Guide](https://docs.uipath.com/activities/other/latest) for more details and examples, as well as how to [Manage Activities Packages](https://docs.uipath.com/studio/docs/managing-activities-packages) . Additionally, you can create custom activities to better automate processes based on your needs.

There are two major steps required to create a custom activity:

1. [Writing the custom activity code](https://docs.uipath.com/sdk/other/latest/developer-guide/writing-the-code-for-your-custom-activity#writing-the-code-for-a-custom-activity).
2. [Adding the external assembly (.dll) in UiPath Studio](https://docs.uipath.com/sdk/other/latest/developer-guide/adding-the-external-assembly-dll-in-uipath#adding-the-external-assembly-dll-in-uipath-studio).
:::note
The following components are required to create a custom activity:
* [Microsoft Visual Studio](https://www.visualstudio.com/) with the **.NET desktop development** workload installed.
* [NuGet Package Explorer](https://github.com/NuGetPackageExplorer/NuGetPackageExplorer/releases).
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