What are the 7 levels of classification for endangered species?

The 7 levels of classification for for endangered species is as follows:

• Data Deficient (DD) 
• Least Concern (LC) 
• Near Threatened (NT)
• Vulnerable (VU)
• Endangered (EN) 
• Critically Endangered (CR) 
• Extinct In The Wild (EW) 
• Extinct (EX)

For more relevant articles refer to the links given below:

• UPSC Environment and Ecology Questions
• Environment & Ecology Trend Analysis: UPSC Strategy
• UPSC Environment and Ecology