* Field of study: Fields like STEM (Science, Technology, Engineering, Mathematics) often place a higher emphasis on publications than humanities or social sciences. Highly competitive programs in any field will look favorably on publications.
* Program prestige: Top-tier programs receive many applications from highly qualified candidates. Publications can help your application stand out from a very competitive pool.
* Applicant's background: If an applicant has limited research experience, publications can compensate for that lack of experience. Conversely, strong research experience demonstrated through other means (e.g., significant contributions to a published paper from a previous lab, strong thesis work, etc.) might lessen the need for independent publications.
* Funding opportunities: Some PhD programs require or strongly prefer applicants who have secured funding, and publications can increase your chances of receiving grants or fellowships.
In short: While you might get into a PhD program without publications, having them significantly strengthens your application. Focus on strong research experience, compelling letters of recommendation, and a well-written statement of purpose, but publications, if possible, are a powerful addition.