What is injective with example?

Could you please explain what "injective" means, and provide an example to illustrate the concept? I'm trying to grasp the concept but it's a bit abstract for me. Could you break it down into simpler terms? I'm particularly interested in understanding how injectivity applies in the realm of mathematics or cryptography, as I'm exploring its use in my current project. Would you mind guiding me through a real-world scenario or scenario related to my field of interest? Thank you in advance for your assistance.