When is the @JsonProperty property used and what is it used for?

Here's a good example. I use it to rename the variable because the JSON is coming from a .Net environment where properties start with an upper-case letter.

public class Parameter {
  @JsonProperty("Name")
  public String name;
  @JsonProperty("Value")
  public String value; 
}

This correctly parses to/from the JSON:

"Parameter":{
  "Name":"Parameter-Name",
  "Value":"Parameter-Value"
}

I think OldCurmudgeon and StaxMan are both correct but here is one sentence answer with simple example for you.

@JsonProperty(name), tells Jackson ObjectMapper to map the JSON property name to the annotated Java field's name.

//example of json that is submitted 
"Car":{
  "Type":"Ferrari",
}

//where it gets mapped 
public static class Car {
  @JsonProperty("Type")
  public String type;
 }

well for what its worth now... JsonProperty is ALSO used to specify getter and setter methods for the variable apart from usual serialization and deserialization. For example suppose you have a payload like this:

{
  "check": true
}

and a Deserializer class:

public class Check {

  @JsonProperty("check")    // It is needed else Jackson will look got getCheck method and will fail
  private Boolean check;

  public Boolean isCheck() {
     return check;
  }
}

Then in this case JsonProperty annotation is neeeded. However if you also have a method in the class

public class Check {

  //@JsonProperty("check")    Not needed anymore
  private Boolean check;

  public Boolean getCheck() {
     return check;
  }
}

Have a look at this documentation too: http://fasterxml.github.io/jackson-annotations/javadoc/2.3.0/com/fasterxml/jackson/annotation/JsonProperty.html

Without annotations, inferred property name (to match from JSON) would be "set", and not -- as seems to be the intent -- "isSet". This is because as per Java Beans specification, methods of form "isXxx" and "setXxx" are taken to mean that there is logical property "xxx" to manage.