He first won the title in the Hague in 1948 when the world's leading players had a tournament to find a replacement for the deceased Alekhine. He later played closely-fought World Championship matches against Bronstein, Smyslov and Tal.

As he was close to the powers that be, he dominated Soviet chess thinking in the post-war era.

Despite his status as 'first amongst equals' in the chess world he wasn't even a professional! In fact he was an electrical engineer an earned a Phd in that domain. In later life he became interested in the technology behind creating a chess-playing computer.

He died in 1995.

I personally found his games collection to be very instructive and was one of my favourites in my youth. He explained his games with a logical-analytic style, with plenty of explanation. I preferred his approach to one involving detailed analysis, but little to explain the thoughts behind the variations.