China agreed to cede Hong Kong Island to the British Empire, and open the following treaty ports of China for foreign trade: 

Canton (Guangzhou) 
Amoy (Xiamen) 
Foochow (Fuzhou) 
Ningpo (Ningbo) 

Also, Great Britain received: 

21 million ounces silver for compensation 
Fixed tariffs 
Extraterritoriality for British Citizens on Chinese soil 
Most Favored Nation status 

In addition to these indemnities, China allowed British missionaries into the interior of China for the first time, and allowed British merchants to establish "spheres of influence" in and around British ports. 

The treaty left several unsettled issues. In particular it did not resolve the status of the opium trade with China, which was profitable for the British and devastating to the Chinese. The equivalent American treaty forbade the opium trade, but, as both the British and American merchants were only subject to the legal control of their consuls, the trade continued.