For over a decade, there has been a debate among search engine optimization (SEO) experts surrounding the best practice for handling redirects—in particular, the best practice for using status codes for Google: 301 (permanent move) versus 302 (temporary move). Additional considerations include HTTPS redirects (from a less secure HTTP link), page-level redirects for simple moves, site restructuring (hierarchy-based) redirects, and domain redirects. Google also has high standards for web security and began giving search rating boosts for sites loading their pages solely over HTTPS.
With all the variations, Google found a less strict way to handle redirects and pass PageRank value whether or not it's a 301 or a 302 redirect (temporary or permanent).
Google's Webmaster Trends Analyst, John Mueller, stepped in to clarify any confusion surrounding the subject:
IMO SEOs fuss too much about redirects. Use the right one for the job, it's a technical thing, not a SEO thing; it's not voodoo magic.— John ☆.o(≧▽≦)o.☆ (@JohnMu) September 29, 2016
Read more in the technical post by John Mueller.
What does 301 vs 302 really mean?
Consider an example where your favorite pizza joint tells you that they have moved to a similar location across town but they are still at the same old place. What you as a customer care about most is that when you order from them, you can still order your favorite specials, and the pizza quality is equal. The location might change, but if the pizza is still the same, you will be a happy customer. That is what Google cares about. When you move a single page or even an entire category, if your quality and user experience are the same or better, Google is happy. You'll continue controlling that page's search keywords. So, whether it's a temporary move (302) or permanent move (301), ultimately you will continue to have the same PageRank—as long as the experience for the user is the same.