Immigration petitions and applications are formal requests submitted to immigration authorities for specific immigration benefits, such as visas, green cards, or naturalization. In the United States, for example, forms like the I-130 (Petition for Alien Relative) or the I-485 (Application to Register Permanent Residence or Adjust Status) are commonly used for family-based immigration, while the I-129 (Petition for a Nonimmigrant Worker) is used for employment-based visas.