Add-ins are supplemental programs that add custom commands or custom features to Office programs. You can obtain add-ins for PowerPoint at Popular Office downloads or on third-party vendor websites. If you are a developer, you can write your own custom add-in programs by using Microsoft Visual Basic for Applications (VBA).

When you enable an add-in, it adds custom commands and new features to Microsoft 365 programs that help increase your productivity. Because add-ins can be used by attackers to do harm to your computer, you can use add-in security settings to help protect yourself.

Add-ins provide optional commands and features for Microsoft Excel. By default, add-ins are not immediately available in Excel, so you must first install and (in some cases) activate these add-ins so that you can use them. Some add-ins are built in to Excel, such as Solver and the Analysis ToolPak.

Click File > Get Add-ins. Alternatively, you can click Home > Add-ins. You can directly install add-ins from this page or select More Add-ins to explore. In the Office Add-ins box, click Store tab. Browse for the add-in you want.

Get an Office Store add-in. On the Insert tab, look for the Add-ins group. To get new add-ins, select Get Add-ins. To use add-ins you already have, select My Add-ins . The add-ins you'll see will depend on the kind of Microsoft 365 subscription you have.

When you select the Import Settings option during setup, the web add-in counterparts of your existing COM add-ins in classic Outlook for Windows are installed in the new client. The following table lists the applicable COM add-ins and their web add-in counterparts.

Use an add-in while composing a message. Create a new message or reply to an existing one. From the ribbon, select the Message tab, then choose the add-in you want to use. If the add-in doesn’t appear in the ribbon, select Apps to view your installed add-ins.

Sign in to SharePoint. SharePoint is a browser-based app that you connect to through your web browser, like so: Go to office.com, and sign in to your work or school account. In the upper left corner of the window, select the app launcher > All apps > SharePoint.

Add-ins in Outlook.com are programs or utilities that help you automate tasks when you view or create messages. Microsoft has partnered with leading companies to build add-ins that help you get things done right from your inbox.

A COM Add-in is an in-process COM server (an ActiveX DLL) that must implement the IDTExensibility2 interface. All COM Add-ins must implement each of the five methods of this interface: OnConnection, OnStartupComplete, OnAddinsUpdate, OnBeginShutDown, and OnDisconnection.