Software installation question?

[ISKOTB]

OS LION…why some software install normal and others create a disk on the desktop then I have to eject it after the install? Thx

 

[orvn]

From what I understand:

Disk images (.dmg) need to be mounted as drives to view their contents, as opposed to, say packages, which can just be extracted.

Dmg's support good compression and encryption, which is why a lot of apps choose them as a model for distribution.

 

[maflynn]

Some developers deliver their apps by way of DMG which is a disk image that requires it to be mounted. Its probably more a personal preference then any technical reason.