The benefits of contextual advertising are obvious. Firstly, the high accuracy of targeting by geolocation and display time excludes non-targeted impressions and saves budget. The second reason is speed, you can find the the publication in search engines very fast . The same thing happens if we speak about editing, the changes you make appears instantly.
The third reason is saving the budget. You pay only for clicks, and you can adjust the cost per click and the total number of clicks yourself. However, this advantage also contains the main difficulty, you should constantly monitor the cost per click.
The cost per click is determined with the help of auction system. The main task of a contextual advertising specialist is to plan the costs of the advertising budget very well. Also the specialist can search for alternative requests which will be more profitable, it means that the cost per click will be lower, but the effectiveness higher.