Edit in JSFiddle

$(function () {
	var $checkbox = $("#checkbox");
  var $results = $("#results");
  var count = 1;
  
	$("#toggleCheckboxValue").on("click", function () {
  	var isChecked = $checkbox.is(":checked");
    $checkbox.prop("checked", !isChecked);
  });
  
  $("#getCheckboxValue").on("click", function () {
  	var isChecked = $checkbox.is(":checked");
    $results.prepend("<div>" + count++ + ". The value of the checkbox is: " + isChecked + "</div>");
  });
});

<div>
  <input id="checkbox" type="checkbox" />
  <span>Check or uncheck the checkbox and click the "Get Checkbox Value" button.</span>
</div>

<div>
  <button id="toggleCheckboxValue">Toggle Checkbox Value</button>
  <button id="getCheckboxValue">Get Checkbox Value</button>
</div>

<h2>Results</h2>

<div id="results">

</div>

<div style="position: absolute;bottom: 5px;">
Read about this Fiddle at: <a href="http://jsdev.wikidot.com/howto:6" target="_blank">How To: jQuery - Get and Set a Checkbox Value</a>
</div>

body > div {
  margin-bottom: 20px;
}

button {
  margin-right: 10px;
}

#results {
  min-height: 50px;
  border: 1px solid lightgrey;
  padding: 5px;
}