The Office 365 app launcher, sometimes known as the waffle due to the icon's familiar shape, is O365's feature menu. It provides access to the various services available in your Office 365 tenant in a similar way to the Office 365 home page, except the waffle is available from all services within O365. Waffle menu buttons are called tiles and the menu can be personalized at the end-user level. The waffle is essentially the Start Menu of O365 because it provides access to O365 services and settings like the Start Menu in does for Windows.
Note that there are three sections to the waffle menu: home, new, and all.
Ultimately, it's likely Microsoft will aim to make the waffle menu the global menu for an organization's entire intranet/internal system, with tiles supported for legacy tools, other cloud services (e.g., expense report and payroll websites), and outside websites (e.g., online libraries and research tools). However, currently, the functionality isn't quite there to pull this off due to its limited configurability from the admin level. Generally, the waffle menu provides access to tools and services built into O365, with some limited ability to link to outside sources. The menu automatically hides tiles to services you do not have access to.
The default tools available on a tenant are shown below. Your experience could be different, especially if your email system exists on your organization's servers (rather than Microsoft's).
- Mail (part of Outlook)
- Calendar (part of Outlook)
- People (part of Outlook)
- Newsfeed (part of SharePoint, not Yammer)
- OneDrive (OneDrive for Business, not consumer OneDrive)
- SharePoint (SharePoint Online, not any other version)
- Tasks (part of Outlook)
- Word (Microsoft Word Online, not the client application)
- Excel (Microsoft Excel Online, not the client application)
- PowerPoint (Microsoft PowerPoint Online, not the client application)
- OneNote (Microsoft OneNote Online, not the client application)
- Admin (available only to O365 administrators)
- Security & Compliance (likely available only to O365 administrators)
- Power BI
- Dynamics 365
As an end user, you can personalize how the waffle menu appears. You can move tiles, remove them, change their sizes, and add apps that you've installed. To move a tile, click and drag it to move it to a new location in the menu.
Unfortunately, tenant admins have limited oversight of the content on a user's waffle menu. Custom tiles can be created and added to the "all" menu in the launcher, but only an end user can add that tile to their "home" menu.