Most confusion about U.S. immigration comes from a handful of ideas that nobody explains clearly. This guide covers those ideas. Once they make sense, every individual category becomes much easier to read.
A visa is not permission to stay
A visa is a travel document placed in a passport by a U.S. embassy or consulate abroad. It lets you travel to a U.S. port of entry and ask to be admitted. That is all it does.
At the port of entry, a Customs and Border Protection officer decides whether to admit you, in what classification, and for how long. That decision is recorded on Form I-94, which you can look up at i94.cbp.dhs.gov.
Three consequences follow, and they surprise people constantly.
Your visa can expire while you are lawfully in the United States. That is normal. The I-94 controls your stay, not the visa.
Your I-94 can expire while your visa is still valid. That is an overstay, and it is a serious problem.
A valid visa does not guarantee entry. Officers can and do refuse admission.
Canadians and travellers using the Visa Waiver Program often have no visa at all, which is a separate track described in the visitor and transit guide.
Nonimmigrant versus immigrant
Nonimmigrant categories are temporary. You come for a defined purpose and leave when it ends. B, F, H, L, O, TN and the rest are nonimmigrant categories.
Immigrant categories lead to lawful permanent residence, the green card. Family preference, employment preference and the diversity programme are immigrant categories.
The intent problem, and why dual intent matters
For most nonimmigrant categories, section 214(b) of the Immigration and Nationality Act presumes every applicant intends to immigrate. The applicant must overcome that presumption by showing ties to their home country and a temporary purpose. Most visitor and student refusals are 214(b) refusals.
Some categories are exempt. H-1B and L-1 are dual intent by statute. You may hold that status and pursue a green card at the same time without harming either. O-1 is treated similarly in practice. E and certain others sit in a middle ground.
Categories such as F-1, J-1, TN, E-3 and H-1B1 are not dual intent. Filing an immigrant petition while in those statuses creates real risk at renewal or at the border. This single point reshapes many people's plans.
Priority dates, quotas and the Visa Bulletin
Immigrant categories other than immediate relatives are capped. Roughly 226,000 family preference visas and 140,000 employment based visas are available each year, and no single country may take more than seven percent of the total.
That per country limit is why applicants born in India, China, Mexico and the Philippines wait far longer than applicants born elsewhere with identical qualifications. It is a rule about country of birth, not citizenship, and a spouse's country of birth can sometimes be used through cross chargeability.
When a petition is filed, it receives a priority date, which is the family's or worker's place in line. Each month the State Department publishes the Visa Bulletin with two charts.
Final Action Dates show which priority dates can actually receive a green card this month.
Dates for Filing show which applicants may submit their applications early, so the paperwork is ready when a number becomes available. USCIS announces each month which chart adjustment applicants may use.
Dates move forward, but they can also move backward, which is called retrogression. That happens when demand in a category exceeds supply mid year.
Two ways to get the green card
Adjustment of status is the route for people already in the United States. File Form I-485, and usually also Form I-765 for a work permit and Form I-131 for travel permission. You stay in the country while it is decided.
Consular processing is the route for people abroad. After the petition is approved, the case moves to the National Visa Center, which collects fees, the DS-260 application and civil documents, then schedules an interview at the embassy.
Which route is available depends on how you entered, whether you kept status, and where you are now. People who entered without inspection generally cannot adjust status, with narrow exceptions.
Petition, then application
Almost every route has two stages, and mixing them up causes real confusion.
The petition establishes the relationship or the job. Family cases use Form I-130. Employment cases use Form I-140. Temporary work cases use Form I-129.
The application is the request for the visa or the green card itself, made by the individual.
An approved petition is not a visa and does not allow you to enter, live or work in the United States.
Inadmissibility
Even a perfect petition fails if the person is inadmissible under section 212(a). The main grounds are health, criminal history, security, public charge, prior immigration violations, misrepresentation and unlawful presence.
The unlawful presence bars catch people most often. More than 180 days of unlawful presence followed by departure triggers a three year bar. More than a year triggers a ten year bar. Waivers exist, including the provisional waiver on Form I-601A, but they require proving extreme hardship to a qualifying relative.
Public charge screening has intensified in 2026, including new guidance on immigrant visa applicants from certain countries and renewed use of public charge bonds. See the U.S. Visas News page.
Status, out of status, and unlawful presence
These three terms are not the same.
In status means you are complying with the terms of your classification.
Out of status means you have violated those terms, for example by working without authorisation.
Unlawful presence is a technical term that generally begins when your I-94 expires, or when an officer or judge finds a violation. It is what triggers the three and ten year bars.
A person can be out of status without accruing unlawful presence, which is why the historical duration of status rule mattered so much for students. That rule is now being replaced by fixed admission periods under a DHS final rule scheduled for 15 September 2026, which is discussed in the study guide and the 2026 policy guide.
Where to check things yourself
- Directory of Visa Categories
- Visa Bulletin
- USCIS Processing Times
- Visa Appointment Wait Times
- USCIS Case Status Online
- USCIS Policy Manual
TR Immigration is an independent immigration information platform. It is not a law firm. Nothing here is legal advice, an eligibility determination, or a prediction about your case. Rules and fees change often, so confirm anything you rely on against the official page it links to.