Broad match modifier restricts the queries triggered by a broad match keyword to the inclusiveness of all the words modified in the keyword. A '+'symbol is used just before the modified word, which means any query triggered through them must include the modified term or its close variants.
For example, if I use modifier in the keyword, say, purple flowers online delivery. I may use it for all, some or one of the word in the keyword. If my concern is, it should not trigger ads on green, blue ... flowers, I may use modifier for the word purple and make it, +purple flowers online delivery. It solves my problem. It won't show on any search term which doesn't include the term purple. Additionally, if the advertiser want to show ads only to people who are interested in delivery, then modifier should shift either only to delivery or both to purple and delivery. This is the basic part of the usage of the modified broad match
We shall now explore further, the practices which may deliver better targeted ads.
Use to limit the exposure of ads to certain brand search terms
It is particularly beneficial for tech support business, who would like to avoid the exposure of Mcafee antivirus ads on norton or avg. To achieve this, simply use modifier for all the terms containing mcafee, like +mcafee support, +mcafee antivirus support etc., Similarly, in other adgroups containing norton use +norton, in all keywords. In hp printer adgroup, use +hp throughout the adgroup and so on.
Use to gain exposure on some rare terms
One may use to gain exposure on terms which attracts little traffic on related terms. So, some location like +location, is useful, or +term can also be used. It is same as we earlier used "location", or "term", phrase match keywords.
Use to improve CTR & Quality Score
An adgroup themed on roses, may contain +roses in all the keyword and this will improve the CTR & quality score of entire adgroup.