In the current scenario, there is a trend in online marketing: Review products.
Most of the blogger review about the products which are received by companies for free. Companies send bloggers free products to review or give away in return for a mention in a blog. But recently Google introduces some guidelines for bloggers who writing the post or companies who supplying the products. Before post reviews about a product, remember few things refer below:

1. Use of No-follow tags

Companies sometimes urge bloggers to link back to

  • Company's business website
  • Companies social media accounts
  • Merchant's page that sells products
  • Review services page featuring reviews of the product
  • Company's mobile app on an app store
Bloggers should use nofollow tag on all such type of links as these links didn't come about organically. Companies or the marketing firms can do their part by reminding bloggers to use nofollow tag on these links.

2. Disclosure of Sponsorship

As a user you would want to know when you’re viewing sponsored content. There are few laws in some countries that make disclosure of sponsorship mandatory. You can put the disclosure content anywhere in the post; however, the most useful placement is at the top in case users don’t read the entire post.

3. Compelling and Unique Content

As a successful blogger you always give a reason to your visitor to come back on your blog. You might try to become the go-to source of information in your topic area. Provide the unique content that only you can create.