I have had a couple of questions emailed to me so I hope the answers below are a help, if not then please ask again! I don't claim to be an expert, the info below is what I have learnt over several years of crafting.
Even now there are times I still get confused about which ink pad is better for the task in hand and one of the things I have done to help me is to write on the lid of the ink pad what I generally use it for. It is a simple thing to do and when you are working away it is easy to forget what you are doing and stamp with the first ink pad you pick up.
Dye based ink pads (Distress Ink pads, Adirondack Dye ink pads these are usually in a cream colour case, Archival, Memento ink pads etc, there are many on the market) are a must for most crafters. These generally are quick drying and work well on porous surfaces. If you use a dye based ink pad on a glossy card/paper you may find it never fully dries and will smudge. Although permanent not all are waterproof which is great if you are looking for a water colour style effect and want to spritz the image but not great if you don't! Some ink pads are fade resistant and permanent and some are not so you will need to read the label to see which are which. I use a black Memento dye based pad with my Copic markers.
Pigment based ink pads are slow drying so are perfect for heat embossing as you get enough time to add the embossing powder. Pigment ink sits on top of the card/paper surface so again using on a glossy card/paper may create drying problems unless you are heat embossing. Pigment inks come in a variety of finishes.
Fast drying archival pigment inks are available (Tsukineko Brilliance Dew Drop), these dry well on vellum, acetate, photo paper & shrink plastic. These have a pearlescent finish.
Solvent based ink pads are quick drying and permanent. They can be used on most surfaces and red/grey rubber stamps, however some of the clear stamps will be affected by them so its best to read the info on the stamp packaging.
I use Stazon in black and brown and I am never without it. Solvent based ink is not great to use if you are colouring in with Copic markers as it smudges. Warning! If you are using a solvent based ink pad over a long period of time make sure you use in a ventilated area (my son will testify that not opening doors and windows creates giggly women trying their best to stamp straight!!)
I hope that the above info is helpful, your local (independent) craft shop will have more expert advice and help if you really get stuck.