The Department of State (DOS) issues a certain number of visas each year for certain visa categories. It takes into account numerous factors as well as various categories including family-based and employment-based categories. DOS releases a Visa Bulletin each month listing the visa availability by preference category and country of birth. Your priority date is the date you file an immigrant petition. (limited exceptions apply).
Once you receive a priority date, you will know whether there is a visa available for your preference category and country. Make sure you check the Visa Bulletin each month, since your priority date can become current or it can also retrogress depending on visa availability. It’s until your priority date becomes current, that you will be eligible to apply for permanent residence.
The visa bulletin for April 2014 is now available. Check your priority date. April 2014 Visa Bulletin