Generally speaking:
* Highly Selective Programs: Engineering (especially aerospace, electrical, and computer), Computer Science, and certain specialized areas within other colleges are extremely competitive. Expect a very high GPA, strong SAT/ACT scores (though test-optional policies may apply), impressive extracurricular activities, and compelling essays. Admission rates for these programs are often in the single digits or low teens.
* Moderately Selective Programs: Many other programs within Purdue's various colleges fall into this category. You'll still need a good GPA and decent standardized test scores (if required), but the competition isn't as fierce as in the highly selective programs. Admission rates are likely in the teens to mid-twenties.
* Less Selective Programs: Some programs within the university may have higher admission rates, but this doesn't necessarily mean they are less rigorous. They might simply have a larger number of available seats.
In short: Purdue is a large, research-intensive university with a diverse range of academic programs. The difficulty of admission varies significantly depending on your intended major. While some programs are extremely competitive, others are more accessible. You'll need a strong academic record, but the specific requirements will depend on your chosen field of study. Check the admission statistics for your specific program on Purdue's website for the most accurate assessment.