Why are we seeing new variants of common viruses emerge?

We see new variants of common viruses because they change a little bit each time they spread from one person to another, like how your favorite toy might get slightly different colors or shapes after being passed around the playground.

Imagine a virus is like a copy machine. Every time it makes a copy of itself inside a new person, sometimes it gets a little mixed up, kind of like when you copy a drawing and the lines get wobbly or smudged. That mix-up is what we call a variant.

When lots of people catch the same virus, it has more chances to make new copies, and with each copy, there’s a chance for a small change. Think of it like passing around a ball in a game: every time someone catches it, they might tweak how they throw it next. Over time, these small changes can add up, giving the virus new powers to spread or avoid being caught by our body's defenses.

So just like your toy gets new colors and shapes when you share it with friends, viruses get new versions when they move from one person to another!