Minify JS and CSS
Minification get rid of the following-:
* White space character
* New line character
Merge JS and CSS
If your website has lot of files, it has to make requests for each and every file. If you can merge the multiple files into a single one,then it only has to request a single file. So the response of the website will be better.Merging helps us to combine lots of JS and CSS files into a single one of there own.