Bandwidth throttling is the intentional slowing or speeding of an internet service by an Internet service provider. It is a reactive measure employed in communication networks to regulate network traffic and minimize bandwidth congestion. Bandwidth throttling can occur at different locations on the network.
Internet shaping is the lowering of available bandwidth by the Internet Service Provider (ISP) to a customer when that customer has exceeded their monthly limit. It's common practice in South Africa so that ISPs can continue to provide internet to customers even when they've exceeded their quota.
Contention Ratio (or over subscription ratio) is the number of users sharing the same data capacity. The lower the contention ratio the higher the quality of service. A 50:1 contention ratio means that up to 50 broadband customers are sharing the same bandwidth at any one time.