Cumulative updates aren't exactly new as far as Microsoft is concerned, but the recent batch for Windows 10 benefits only older versions of the operating system.
The cumulative updates will be focused at Windows 10 April 2018 Update (version 1803) and versions before this. Note that Windows 10 October 2018 Update (version 1809) and May 2019 Update (version 1903) will not be a part in this cumulative update rollout. Most likely, both Windows 10 version 1809 and 1903 will receive new cumulative updates in the coming days before the end of the month.
It should be noted that from the patched versions of Window 10, only the April 2018 Update is still supported for Home and Pro SKUs. Older versions are only serviced for Enterprise and Education SKUs and as part of the Long-Term Servicing Channel (LTSC).
The following are the Windows 10 versions getting patched and the cumulative updates they received on July 16:
Windows 10 version 1803: KB4507466 (OS Build 17134.915)
Windows 10 version 1709: KB4507465 (OS Build 16299.1296)
Windows 10 version 1703: KB4507467 (OS Build 15063.1955)
Windows 10 version 1607: KB4507459 (OS Build 14393.3115)
You can check out the highlights of updates right here, but to cut it short, the Windows 10 version 1803 cumulative update's most significant fixes are related to app permissions and for a screen reader bug. In the words of Microsoft:
"Addresses an issue with opening or using the Window-Eyes screen reader application that may result in an error and prevent some features from functioning as expected.
Addresses an issue that may fail to keep App permissions settings when you select Keep my files after selecting Reset this PC."
These cumulative updates are now available from Windows Update and the Microsoft Update Catalog, and you can get them by simply checking for updates in Settings > Update & Security > Windows Update > Check for updates.
Most Windows users have no problems installing updates as these are done automatically. However, there are cases in which Windows 10 may not successfully install the cumulative updates successfully. If this Windows Update mishap happens to you, or if you multiple PCs, you can use the Windows Update Catalog to download and install the updates manually.
In other Microsoft news, the company has already shipped a new cumulative update for Windows 10 version 1903, or May 2019 Update, to insiders in the Release Preview ring. More announcements from Microsoft are to be expected soon.