Harvesting Terms:

Node: harvestable clump of resources. They are found in all zones, and in newer zones, match the terrain in which they are found (rocks in caves, for instance, or dens around animal areas). In older zones, you can find any kind of node randomly placed. Each node has three chances to gather one or more resources (up to 10 at once) when you click them with the hand tool. Nodes are governed by the game's Random Number Generator so there's no guarantee or system to get rares or more commons at any given node.

Harvesting skills include mining, foresting, gathering, trapping and fishing (and you will have a hotkey for all in your abilities section of your knowledge book). Each type of node requires a specific skill in harvesting. Remember to skill up in each area as you level up in the game, as some higher level quests require corresponding levels of harvesting skills.

Type of Node:
Each zone and tier will have slightly different looking nodes, according to the environment, and require one of the five skills to gather, but they all will fall under these basic categories:
Ore (mining): metal, loams for the alchemists
Stone (mining): soft metals and gemstones
Den (trapping): animal products, such as hides and meat
Wood (foresting): organic structural materials, also called "pile of bones" in Tier 2
Roots (gathering): fiber-type roots
Plants (gathering): foodstuffs, such as berries and vegetables
Schools of fish (fishing): fish meats and products

Harvesting skills:
As with all other skills harvesting skills progress by +5 for each level you gain, tradeskill or adventure - whichever is the highest determines your level.

Tier: In EQII, a tier is the level range of the harvestable items. Each tier requires a progressively higher skill level for each type of harvesting

Tier 1 - Level 01-09 - Skill 0+ :: Queen's Colony, Outpost of the Overlord, Forest Ruins, Oakmyst Forest, the Caves, the Peat Bog, the Ruins, the Sunken City, the Sprawl, the Graveyard, Greater Faydark, Darklight Woods, Timorous Deep
Tier 2 - Level 10-19 - Skill 20+ :: Antonica, Commonlands, Vale of Shattering (access quest needed), Greater Faydark (eastern portion near Crushbone and the spires), Darklight Woods, Timorous Deep
Tier 3 - Level 20-29 - Skill 90+ :: Thundering Steppes, Nektulos Forest, Zarvonn's Tower (Eternal Gorge), Butcherblock Mountains
Tier 4 - Level 30-39 - Skill 140+ :: Enchanted Lands, Zek, Cove of Decay (access quest needed), Bloodskull Valley (access quest needed), Steamfont
Tier 5 - Level 40-50 - Skill 190+ :: Rivervale, Feerrott, Everfrost, Lavastorm, Steamfont (wetlands and area near it)
Tier 6 - Level 51-60 - Skill 240+ :: Sinking Sands, Pillars of Flame, Lesser Faydark
Tier 7 - Level 61-70 - Skill 240+ (some zones may be 250):: Loping Plains, Tenebrous Tangle, The Barrens, The Bonemire (node types here are based on island location)
Tier 8 - Level 71-80 - Skill 340+:: Kylong Plains, Fens of Nathsar, Kunzar Jungle, Jarsath Wastes

How to Harvest:
Double clicking the node will grab one set of harvestables, which can be multiples of the same thing. Keep going until the node disappears. The better your skill, the fewer instances of gathering nothing will occur.

Rares are meant to be rare, so when you get one the UI will alert you with an alert sound and a message to let you know you got a goodie. A rare harvests include imbued items.

Tip: Speed up the harvesting process by using the F key when the node is targeted, or for even faster harvesting, use a harvesting hotkey and cue up a second attempt while performing the first.

Harvesting tools give you a +1 skill bonus, and a reduction of the base speed of five seconds to a maximum reduction of 2.5 seconds per harvest attempt (this depends on racial abilities and casting speed). Tools do need to be attuned. Right click them to attain a 10 day buff for your harvesting speed increase.

Wood tools are based on your adventuring level, and can be used starting at level 20, with better tools for level 30, 40, and 50, and then 70.

Tinkered tools are based on your crafting level and can be used at level 30, 40, and 66 for fishing, logging, and mining.

You can leave the tools in one of your bags and simply drag them to a hotbar key. Pressing that key will auto-equip the harvesting tool for you.

Woodworker crafted tools to increase base speed:
Shovel - gathering
Pick - mining
Trap - trapping
Net - fishing
Saw - foresting

Automated Tinker Tools, which increase skill as well as speed up the process:
Pick for mining
Shears for gathering and foresting
Net for fishing

Harvesting

Light sources
Under rares we find the semi-rare "light source" resources which can be used by various tradeskill classes to produce an imbued version of a pristine piece of armor, weapon or jewelry. All lightsource resources within a tier can be used for that given tiers' imbued recipes. Light sources are used directly in the final recipes, hence you do no longer require the need of an alchemist to make an extract.

Special Heritage Quest Harvests: blue-silver sheet (ore), perfectly cut purple geode (stone), a perfect osseous lumber (wood), a strip of supple leather (den). Used in the Draco Mortuus vos Liberatio heritage quest.

Additions to this table for Tier 8:

Ore:
ferrite cluster, mineral salt loam
Rares: incarnadine cluster, silicate loam

Gem:
rough kunzite, deklium cluster
Rares: tynnonium cluster, rough fire emerald

Roots:
Lichenclover root
rare: mantrap root

Wood:
redwood lumber
rare: mahogany lumber

Dens (in T8 these only drop pelts):
bristled pelt
rare: hidebound pelt.
For T8 faction-purchased food recipes that call for meat, you need to kill the appropriate creature to get: brute flesh, devourer meat, hornet meat, drachnid meat and mountain giant meat.

Bushes:
torsis tea leaf, cabilis cocoa bean, cranberry, succulent petal
rare: mantrap

Fishing:
baracuda, king prawn
magma rock fish (requires a collapsible fishing pole and swimming in Jarsath wastes.)