Spider Silk

A semi-rare item. Because of its heavy use in obtaining addons as well as its low drop rate, spider silks have a good market value. However, this is declining with the introduction of many new areas with Giant Spiders and Crystal Spiders. Low levels can and often do complete the Tarantula task of Killing in the Name of... Quest to get a high chance of looting one from the boss, Hide. Due to a (now fixed) game bug that allowed people to kill an unlimited number of task bosses using field runes, spider silks were heavily inflated even on Aurora and Aurera where World Transfer is forbidden.
It looks the same as Recharging Tarantula Trap and Steel Spider Silk, which is also often used to scamming people through trade.

It is hard to see Spider Silk on light backgrounds due to it being white and stringy. Inside a container, it looks like this:

100 of these (10 Spool of Yarn) are needed for Barbarian Outfits Quest.
100 of these (10 Spool of Yarn) are needed for Assassin Outfits Quest.
100 of these (10 Spool of Yarn) are needed for male Summoner Outfits Quest.
100 of these (10 Spool of Yarn) are needed for female Mage Outfits Quest.
1 is needed for What a foolish Quest.
10 of these can be traded for a Spool of Yarn with Marina.

With update 8.5 this item was renamed from Giant Spider Silk to Spider Silk. This is because (in an earlier update?) other monsters such as Crystal Spider began dropping them.