Different sets of search results are set to appear on mobile phones and PCs for the same search terms, as Google will start indexing mobile websites separately.

Search Engine Land reported that Gary Illyes, a webmaster trends analyst at Google, announced in his keynote address at Pubcon digital marketing conference in Las Vegas on Thursday that Google would move on from its current single index of documents to a separate mobile search index, which will become the primary one.

The primary one would be used by Google to respond to search queries. Illyes also confirmed to Search Engine Land that the development will take place in the "coming months." He had indicated that Google was experimenting with separate mobile indexing on Twitter in September last year.

It’s not surprising that Google is concentrating on mobile users since the PC market is on a decline, while the mobile device market is set to do better in 2017.

The company also announced that it will start penalizing websites with intrusive pop-up ads on smartphones. In October last year, Google introduced Accelerated Mobile pages, which will allow mobile web content to load more quickly.