How Does the Ringgit Become Stronger or Weaker?

We often hear about how the Ringgit is becoming weaker or stronger when compared to other currencies. For example, people often talk about how at one point, the Ringgit to the Singapore dollar was 1:1, but now one SGD is more than RM 3. More commonly we often discuss the ringgit to the US dollar. But how does any of this work, exactly?

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