IP address blocking is the process of preventing a user or machine originating from a specific IP address to connect with a server. Several or ranges of IP addresses can be blocked and the blocking can be done for mail or website servers.
IP address blocking has many uses in ecommerce or digital marketing contexts. It can be used for:
preventing bots to access a website - for price retrieving for instance
preventing transactions orginating from some countries
blocking email spammer
blocking some addresses to see or click ads
The latter practice can be used by advertisers on PPC search engine platforms to prevent competitors to consume a budget.
See also IP address filtering which can have a slight different meaning.
An IP address generator for blocking countries: