What is the rank of injective?

Could you please elaborate on the concept of "the rank of injective" for me? I'm interested in understanding how it applies in the realm of mathematics, particularly in the context of functions and mappings. Could you explain what it signifies and how it is determined? Is there a specific formula or procedure used to calculate it? Also, would you mind giving some examples to illustrate the concept? It would be helpful if you could provide insights into its practical applications, if any, in the field of cryptocurrency and finance. Thank you for your assistance.