Hoping someone could help me with this.
Basically want to know what an ASR router is used for and why would I need to use one?
I suggest you take a look at the datasheets for more detailed information.
Wassim, I do believe he's referring to the ASR series of routers that are produced by Cisco, which you can read about via the links posted by Aaron.
angelo, generally speaking you're looking at ASR routers when you need to provide advanced services at wirespeed, high bandwidth specialized WAN connectivity(SONET, DS3+, etc). The ASR series is very powerful while at the same time not taking up a huge footprint. You can look at the 1000 series or the 9000 series, depends on your needs.