Uzbek is a Turkic language spoken by the Uzbeks.  There are two main varieties; Northern Uzbek is spoken in Uzbekistan, Kyrgyzstan, Kazakhstan, Tajikistan, Turkmenistan, and China.  The Southern variety is spoken in Afghanistan and Pakistan.  Within those two main groups are many smaller dialects.  Depending on region, Uzbek has been influenced by Russian, Persian, and Arabic.  

The native or second language of around 32 million speakers around the world, Uzbek is the second most widely spoken Turkic language (after Turkish).

While there are a variety of reasons that Uzbeks have immigrated to the United States, the main one is to follow economic opportunity.  Low salaries and lack of opportunity in Uzbekistan makes it very hard to support a family.