You may know that the R01 is NIH’s standard research project grant. But what about the hundreds of other activity codes NIH uses? Activity codes differentiate between the wide variety of grant programs we offer. Our types of grant programs page can be a huge help in deciphering our lingo. A word of caution: not all NIH institutes and centers (ICs) use every activity code. Look closely at the funding opportunity announcement to determine which ICs participate and for eligibility details.