Shorthanded and longhanded
Shorthanded and longhanded are in poker terms for describing the amount of potential players on a table. Shorthanded refer to a table that includes 5-6 players. This is different from playing longhanded, which involve tables with 7-10 players.
In the latter case, you need to play tighter. Especially in pre flop: even if only three players have checked before it's your turn, the quality of their hands is likely better than three random hands on a shorthanded table. The obvious reason is that the more contenders there are, the bigger are the chances that somebody has excellent hole cards.
One of the most significant differences between short- and longhanded tables is that the value of starting hands is shifting. Some starting hands win and lose attraction depending on the number of opponents.
On a table with about nine contenders, you aren't going for a knockout. If you insist, it's a big risk that you will be swinging against several opponents at the same time and no hand can give you 90% in a pre flop all in-situation against three players! This doesn't mean that you should play defensive with strong hands, but you need to be conscious about the decreasing of hands value per player.
Starting hands well-suited for longhanded games are speculative hands like connectors and suited cards. That's because these kind of hands can beat many players. Now you may say: "Yes, but I think these hands can beat a few players in a shorthanded game also". Yes, that is of course true, but the thing is: the size of your win on a straight or a flush hand depends on how many players you beat. Therefore, it's more motivated to play speculative hands often in longhanded games, since the times when you win it will pay back more non-successful attempts than it does in shorthanded games.
This doesn't mean you should automatically throw away an 8-9 suited then playing shorthanded, but you shouldn't always limp or call a raise with it. One more thing: if cards are playable or not according to the amount of players, it's just one of many circumstances that inflect the outcomes. You will get familiar with more circumstances in other articles on this site.