write a brief summary for each of the following two points that MUST be based on a scientific research paper. .

for each point, you must provide at least one reference:

.- One of the advantages of online marketing is that it is relatively easy to track and measure data. This data can be used to improve marketing campaigns and make them more effective.

- However, one of the challenges of online marketing is that it can be difficult to stand out in a crowded online space. With so many companies and individuals competing for attention online, it can be difficult to get noticed.