Why I can't install iChat?

Question

can some body tell me; why I can't install iChat on OS X Mountain lion MacBook Air?

Answer 1

Hi,
Each version of iChat only works with the OS it came with.
Broadly speaking that means iChat 4 work only in Leopard (OS X 10.5.x) - iChat 3 only works in Tiger (OS X 10.4.x) and so on.
It is actually more important that a subset increase in the OS also has the "right" iChat version.
iChat Updates come in the OS updates.
There is not always an iChat update but it does mean that when it is that version will not work with lower OS versions.
As an example iChat 4.0.8 only works in OS X 10.5.8
Mountain Lion has Messages.
This is iChat+
The iOS version of Messages can send iMessages to iPhone Numbers and Apple IDs or registered devices.
iMessages is Apple's proprietary Messaging service and has been added to what was iChat to create the Messages app for Macs.
The Messages app does everything iChat did (Video Chats, Audio Only Chats, Screen Sharing, iChat Theater, Text chats, File Transfers with some IDs)
It can also register an Apple ID for iMessages.
If the same Apple ID is used on an iPhone and iPad then the iMessages will be displayed on all devices.
7:18 PM      Thursday; January 24, 2013
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
  iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
 Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images."  No, Seriously