Windows Defender is the default antivirus in Windows 10 operating system. For the uninitiated, Windows Defender is more or less like Microsoft Security Essentials solution out there for Windows 7 and earlier versions. Windows Defender in Windows 10 features In Windows 7 and previous versions, the built-in Windows Defender was just a spyware remover. However, the Windows Defender in Windows 8 and Windows 10 helps you get rid of viruses, spyware, and malware as well. On top of that, Scan with Windows Defender context menu entry has been added in Threshold 2 Update so that users can quickly scan files and folders. The Windows Defender in Windows 10 is configured to automatically download and install definition updates from Microsoft servers and requires no user intervention. The Defender gets definition updates via Windows Update service, and if you have turned off automate Windows Update for any reason, you need to manually update Windows Defender offline. Definition updates for Windows Defender in Windows 10 If the Windows Defender is not automatically downloading and installing updates for any reason or if your PC is offline, you can manually download Windows Defender updates from Microsoft and then install updates with a click. Here is how to download Windows Defender definition updates from Microsoft and install them on a Windows 10 PC. Download and install Windows Defender updates offline in Windows 10 NOTE: Usually Microsoft releases Windows Defender updates at least once a day, and recommends you download and install every day for good level of protection. Step 1: Since Defender updates are separately available for 32-bit and 64-bit, before visiting Microsoft website, you need to check the type (32-bit or 64-bit) of your Windows 10 operating system. To check if you’re running 32-bit or 64-bit Windows 10, right-click on the This PC icon in the File Explorer and then click Properties. Under System section, you will see type as 64-bit operating system or 32-bit operating system. Step 2: Visit this page of Microsoft, and scroll down. As you can see in the picture below, the webpage displays version of latest Defender definition updates as well as the date and time at which the update was uploaded. Download either 32-bit or 64-bit updates depending on the type of Windows 10 installed on your PC. For Windows Defender in Windows 10, click the 32-bit or 64-bit link next to Windows Defender in Windows 10 and Windows 8.1 as shown in the picture below. The update file will be named as mpas-fe.exe, mpam-fe.exe, or mpam-feX64.exe. Step 3: Once the update is downloaded, navigate to the folder containing downloaded files, double-click on the update file, click Yes button if you see the User Account Prompt to install the update. The update will be installed in a few seconds. If your Windows 10 is offline and you’re using Windows Defender instead of third-party tools, we recommend you update the Defender at least three days once if not possible to update every day.