Antibody vs. Antigen: What's the Difference?
Read the comparison below, or explore it visually. Create a visual lesson comparing antibody and antigen using available credits or plan allowance.
They're two sides of an immune battle. An antigen is the trigger — a molecule (often on a virus, bacterium, or other invader) that your immune system recognizes as foreign. An antibody is the response — a Y-shaped protein your body makes to lock onto that specific antigen and mark it for destruction. Antigen is the lock; antibody is the custom-made key.
At a glance
| Antibody | Antigen | |
|---|---|---|
| What it is | Defensive protein your body makes | Foreign marker that triggers defense |
| Origin | Made by your immune system | Usually from an invader (or vaccine) |
| Role | Finds and neutralizes the threat | Identifies something as foreign |
| Shape fit | Custom-shaped to one antigen | The specific shape being matched |
| Analogy | The custom key | The lock it fits |
Which should you use?
An antibody is the body's targeted weapon — once it has 'learned' an antigen, it can recognize that same threat fast in future, which is the basis of immunity and vaccines.
An antigen is anything the immune system flags as foreign — a piece of a virus, a bacterial surface, or the harmless fragment in a vaccine that teaches your body what to fight.