[jcoby]

You can mark ingredients for search in the crafting menu (press 'T' on the pc version I think) and any item that has those ingredients will have a spyglass next to the item name when you look at the item. I have gears, springs, adhesive, and aluminum all marked.

I think they tried to force you to learn how to use this system when you need a circuit board to build a sentry for your settlement and the closest one is in the red rocket in a phone. I just got mad and used the internet. It wasn't until about 20 hours into the game when I wanted to start building mods for the guns that I noticed it.

[soylentcola]

In addition to the spyglass icon, if you are facing a chest/item that contains materials you've marked, they have a blue "glow" overlay that makes them stand out. Pretty sure that's part of the base game since the only mods I've installed are one to add more songs to Diamond City Radio and one to tweak lighting and improve ambient occlusion (just basic post-processing tweaks). Don't think the blue glow on tagged materials is part of either mod.

[lfowles]

That sounds like level 2 of the scavenging perk in the INT tree. Level 1 was finding screws and uncommon materials when scrapping guns, level 2 is finding rare materials when scrapping guns as well as highlighting tagged components in the game.