Remove textbox value when click on textbox

We saw many search textbox contains the word 'search' and when we click on the text box the text will remove. We are using javascript to do this.

The code is as follows

<input type="text" onblur="javascript:if (this.value == '') { this.value = 'Search'; }" onfocus="javascript:if (this.value == ''Search'') { this.value = ''; }" value="'Search'" id="txtsearch" name="txtsearch">