Retro Gaming (also known as classic gaming and old school gaming) is the act of playing older consoles such as the Nintendo Entertainment System and games on said consoles as opposed to playing on newer consoles. Most often the consoles that are played are often discontinued and "obsolete".
Retro gaming is growing in popularity and many indie game developers are taking notice by using games from the 8 and 16 bit eras as inspiration for new games such as Shovel Knight and Axiom Verge.
Many companies are even making new technology to aid these older consoles such as HD attachments and new consoles altogether, such as the Retron 5 and the NES Classic. There are even some small companies that continue to make homebrew games for retro consoles.
Services such as the Nintendo Virtual Console allow newer gamers to play older games without needing the consoles which they might not own, and allow older gamers to revisit games they no longer own or are damaged.
Retro gaming is a positive aspect of gaming because it helps to show that you don't need the most powerful technology to make a good game and many of these older games still hold value to people. Playing these older games also let people appreciate how gaming has evolved over the years and how things were done before with the hardware limitations of that time. Retro gaming also gives older gamers the opportunity to check out games and consoles that they didn't own during their childhoods. Systems like the NES Classic and SNES Classic make it easier for people to revisit old school games.
Modern gaming consoles have many features that frequently irritates gamers such as Micro-transactions, Retro gaming is free of all that which makes it more appealing to gamers who don't like those inconveniences.
Nostalgia is usually a strong factor for older Retro gaming, as many games and franchises in older consoles are unavailable in modern consoles. This is to the point that some companies are making "Spiritual Successor" games, games with new IPs that play almost exactly the same those older franchises that major publishers don't want to make games for anymore. Recently older game franchises have been getting revivals, such as the case of Crash Bandicoot N. Sane Trilogy.