Why downloading speed is higher than upload speed ?

Because most people download content a lot more than they upload it. Streaming a Netflix movie does not require that much info to be sent upstream.

If you are using an ADSL connection then the "A" stands fo "asymmetric" - most of the bandwidth (usually 80%) is dedicated to download with typically 20% for upload.
See previous post for the reasoning behind that. It's not just movies - consider an ordinary web browser request vs the size of the content that you get back.

Thanks alot for replay

And the reasoning behind setting it up like that includes the idea that your upload is somebody else's download, as most ISPs also are hosting providers.
By limiting upload speeds, they can offer more bandwidth to their customers who rent those servers without having invest in more hardware.

It's not that it's a technical limitation that download speeds must be faster than upload speeds. Both your download and upload speeds have been capped by your ISP. Because most people mostly download, and the only reason you would have a significant need to upload a lot is if you're using P2P, running bots, running servers, consuming a lot of bandwidth, and/or doing lots of other things that might violate your TOS with your ISP, they cap your uploads lower than your downloads.

There speaks someone who has never been at the end of a 6.5 km ADSL connection.

Nope, I haven't ever had DSL. It shows?

Oh yeah, for years I had 1.8 meg download speed at best. Drove me mad when Apple photos decided to re-download my pictures (5gig) at random intervals thus shutting out everything for seven hours. They obviously weren't long wire ADSL either.
But nowdaysI have about 15 meg via a WiMAX service from a water tower about 20km away. It's heaven.
Or at least I thought it was until this week... I'm in a hotel in Morocco and it has blanket 80meg WIFI, even on the beach. NOW I'm in heaven.

Internet service provider provide better speed for downloading than uploading because on the internet user do downloading activities more comapre to the uploading activities.