In the US, most graduate school applications require you to include:
Transcripts from previous educational institutions
Standardized test scores (such as the GRE or MCAT)
A graduate resume
2–3 letters of recommendation
A statement of purpose
Some programs may ask you to write a personal statement in addition to, or instead of, a statement of purpose. You may also be asked to an interview.
Always carefully read the application instructions for the specific program you’re applying to.