ext4

TRIM support is available on ext4. It is activated by adding discard to the list of mount options. So in /etc/fstab it says something like:

/dev/sdx1        /somewhere               ext4        defaults,discard         1   1

You can also discard the unused blocks manually by using:

fstrim -v /somewhere

The resulting amount of space trimmed may not be the same as the actual space freed on the disk. It is safe to repeat this, for example in a cronjob.

/somewhere: 3 GiB (3267461120 bytes) trimmed

ntfs on windows

TRIM support is available on ntfs and refs. You can check if it's active by using the following command:

fsutil behavior query disabledeletenotify

The response will be like this:

NTFS DisableDeleteNotify = 0  (Disabled)
ReFS DisableDeleteNotify = 0  (Disabled)

A value of 0 means that it's not disabled, so that TRIM support is active.

You can manually trim a drive from PowerShell with:

Optimize-Volume -DriveLetter C -ReTrim -Verbose