If you ever need to redirect users from one page to another — due to website consolidation, new URL or some other reason — the ideal way to do it is via a “301 redirect”. A 301 redirect is considered a permanent change, and Google will use that information to update the search results.
However, it’s long been understood that Google only passed roughly 80% of the “link juice” via a 301 redirect. This means if your old site/page got a great link from somewhere else, you’d indeed get value for that link on your new page, but with a bit of a loss in value.
As of a few months ago, Google’s Webmaster Trends Analyst Gary Illyes confirmed that 301 redirects now pass 100% of their PageRank to the receiving site.
30x redirects don't lose PageRank anymore.
— Gary Illyes ᕕ( ᐛ )ᕗ (@methode) July 26, 2016
To be honest, this doesn’t change much. 301’s were always the recommended way to handle redirects and losing ~20% of the link equity was simply a small price to pay. Now that 100% of that PageRank is flowing through them, sites that are set up properly should gain just a bit more leverage in search results.