Using Immigration Forms
Immigration forms or USCIS forms can be downloaded and are in PDF format. In order to view, print, or fill out these forms, you should use the latest version of Adobe Reader which can be downloaded for free.
To ensure that you complete and submit your application correctly, make sure you carefully read any notices, warnings, or explanations on the Forms Entry Page (FEP) before you print (or download) the form itself, fill it out and send it to USCIS. Also make sure to verify the filing location of the forms for the specific benefit you are seeking.
All the immigration (prefixed with “I”) or naturalization (prefixed with “N”) forms come with detailed instructions about where to file and those instructions will differ with specific circumstances. If you do not file the forms with the appropriate office or with the correct fee, it might result in an application or petition being returned to you and will also result in further delay in processing. It is important to remember NOT to mail your application or petition to the “HQPDI” address on any form, (that address is for submitting comments on the form itself.)
Source: Immigration Direct