When creating your ads for PPC you need to ensure that you have a compelling headline which will stand out to users. As you may know already, if text within your ad matches a search query then that text will be highlights in bold by Google, therefore the best way to get your ads to stand out is to have the whole headline bold by using keyword insertion.
Keyword Insertion allows your ad to use the search query that triggered your ad to be used anywhere in the ad text. For example if a user searches for 'iPhones' your ad could look like this;
Get Your iPhones here
Fast Delivery on all iPhones
This allows your ad text to match exactly what the user is looking for so it is 100% relevant and stands out so the user is likely to click on your ad.
Keyword insertion can only be used if a search query is not too long, and if it adheres to the Google guidelines, if it is a explicit word then Google will not allow it to show within your ad. When using this tool you must enter alternative words in case keywords insertion is not able to be used.