Question: I have use placeholder attribute to give information for user what's the input needed.

1. Is there any browser that's incompatible?
2. How to remove the placeholder when I focus in the textbox?

Answer: 
1. [Many older browsers](http://caniuse.com/#feat=input-placeholder).
2. While you could with JavaScript, **don't do that**. If someone tabs into it, they don't know what they're supposed to input.
> 
> Is there any browser that's incompatible?
> 
> 
> 

Lots, but as `placeholder` is designed to provide a hint (such as an example) and not as a replacement for a real `<label>`, that shouldn't be a problem if you are using it properly.

> 
> How to remove the placeholder when I focus in the textbox?
> 
> 
> 

Trust the browser to do it.

If a browser doesn't support `placeholder` it won't render the text in the first place.