In some cases, they can be used for crawling and indexing
In some cases, they may be used for ranking
Emphasis on the word “some” here. Google has made it very clear that in most cases they will continue to ignore nofollow links as usual.
For most sites, the answer is no — if they want to. Google doesn’t require sites to change, and so far, there hasn’t been a business case for it.
Nonetheless, there are several cases where a website owner might want to implement a new attribute:
Hopefully, they will help Google better understand the sites kazakhstan mobile database they or their contributors are linking to . For example, if a site like Wikipedia made a change like this, it would probably be good for everyone. Or, perhaps Moz would change the way it labels links in user-generated Q&A sections which often link to high-quality sources.
Sites using nofollow for crawl control . For sites with large faceted navigation, nofollow can sometimes be an effective tool to prevent Google from wasting crawl budget. Until Google starts treating nofollow as a crawl "hint," it's too early to tell whether publishers using nofollow in this way will need to make changes, but it may be important to be aware of.
To clarify, if a site is using nofollow correctly today, SEOs do not need to make changes. Although sites are free to do so, they should not expect to improve rankings by doing so, nor should they receive new penalties for not changing.
Still, Google’s use of these new link attributes is likely to evolve over time, and it will be interesting to see, through research and analysis, whether using the nofollow attribute in certain ways in the future does in fact yield ranking benefits.
Which link attribute should be used?
If you choose to change your nofollow links to be more specific, Google’s guidelines are pretty clear, so we won’t repeat them in depth here. In short, your options are.