Since many readers requested more details about consular processing steps, please see below blog post which gives step-by-step details during consular processing for NVC applicants. It also includes latest changes made by State Department on September 2013.
Note: Consular Processing applies to applicant who live/resides outside US. If applicant is inside US, they can choose to either go for
Adjustment Of Status or go outside US and apply for
Consular Processing.
Update (November 2014): National Visa Center No Longer Collecting Original Civil Documents:
http://blog.mygcvisa.com/2014/11/national-visa-center-no-longer.html
Step 1: Once your I-130/I-140 application is approved, USCIS sends it (I-797 Notice of Action) to NVC (National Visa Center). It may takes some time for NVC to receive the petition from USCIS (4-8 weeks). After receiving the petition, NVC will create a unique case number for your application.
If your PD is not current, NVC send you a letter informing you that they have received your petition from USCIS and they will hold it till the PD is current. You do not have to take any action. You will have to wait for PD to be current and then NVC will contact you (see below).
If your PD is current, please see steps below.
Step 2: NVC will send I-864 (affidavit of support) processing fee bill to the petitioner. Please also submit form DS-261 online. DS-261 form replaces paper form DS-3032 (Choice of Address and Agent form).
Submit form(s) online.
Note: Starting September 1, 2013, all immigrant visa applicants will apply
online using Form DS-260 (Application for Immigrant Visa
and Alien Registration). Applicants will
also choose their agent online using Form DS-261 (Choice of Address and
Agent). Applicants
will access both forms on the web at ceac.state.gov.
These
forms replace the paper DS-230 and DS-3032. The National Visa Center
(NVC) may instruct some applicants who previously
submitted Form DS-230 to submit Form
DS-260. Only Diversity Visa and Cuban Family Reunification Parole
applicants will continue
to use the paper forms. If you have
questions or feedback about Forms DS-260 and DS-261, contact the NVC at
nvcinquiry@state.gov or
603-334-0700.
Step 3: Once you have paid I-864 fees (in step 2 above), NVC will send
I-864 (affidavit of support) form to the petitioner. They can also ask you to download I-864 form from their website.
Also see FAQ for Fee Payment:
http://travel.state.gov/visa/immigrants/info/info_3904.html
Tip: NVC will give you one year to pay the fees. NVC will reinstate I-130 after one year, but it may require additional work.
Step 4: Completely fill out I-864 form. Attach any supporting documents and send this back to NVC (do not send it to consulate). Remember to also include the bar code sheet (if applicable).
Step 5: As soon as NVC receives form DS-261, NVC will mail Immigrant Visa (IV) bill to the agent of choice (that you wrote in step 2 above).
Step 6: Once NVC receives the Immigrant Visa (IV) fees, NVC will send Packet 3 to agent of choice. Packet 3 is also called "Instruction Package For Immigrant Visa Applicants". The content of Package 3 will vary slightly depending on the local US consulate (where applicant will be interviewed). Please see FAQ below for typical documents required for Packet 3.