What are keywords?
Keywords are terms used by users in search engine searches.

What are negative keywords?
Negative keywords are terms that should not appear in a Google ad. The definition of these keywords allows you to optimize campaigns, reducing spnding on unwanted search terms, or terms that to not suit your ad. In other words, by identifying which are the negative keywords, you are reducing the spending on clicks that would hardly generate sales or leads.

According to Google, in order to better target your campaign, ensuring that ads will only appear to those who are really interested in your product or service and increase ROI (Return Over Investment), try to create a list of negative keywords with terms similar to your keywords, but that are suitable for customers looking for a different product.

One way to indentify negative keywords is to access Google's Keyword Planner and enter the keywords that you think fit your ad. Then, search the list for keywords that don't match your campaign and that, therefore, you don't want to see associated with your ad - negative keywords.

Types of negative keywords
In Google ads it is possible to define 3 types of negative matching:

Negative broad match
In this match type, the ad will not appear if the search contains all terms of negative keyword, regardless of the order in which the terms appear. However, if the search contains only some of the terms, the ad will continua to appear.

Negative phrase match
In the case of negative phrase matching, the ad will not appear if the search contains the exact keyword terms in the same order, even if the search includes additional terms. These keywords are identified using "" - for example "used bikes".

Negative exact match
As with negative phrase matching, the ad will not appear if the search conains the exact terms, in the same order. The difference in this case lies in the fact that the ad continues to be displayed if the search contains additional terms. These keywords are identified using [] - for example [used bikes].