This is a description of what nootropics are. Nootropics are substances that boost cognition. They increase the amount of neurotransmitters and brain chemicals in the brain. They improve mental functions such as cognition, memory, intelligence, motivation, attention, mood, and concentration. Some nootropics reduce anxiety. Some nootropics boost memory and problem solving skills. Still, other nootropics can act as a stimulant. There are different classes of cognitive enhancers
Hypranootropics: These are powerful relatively non-toxic substances that causes a powerful and sometimes exponential cognitive boosting effect. Permanent. :D
Nootropics: These are relatively non-toxic substances that causes a moderate to powerful cognitive boosting effect. Some of them have mild effects. Permanent.
Quasinootropics: These are relatively non-toxic substances that causes a moderate to powerful cognitive boosting effect,. Usually temporary, but generally causes little to no cognitive damage. They're half-nootropics or semi-nootropics. Some or them have mild effects.
Pseudonootropics: These are fake nootropics. They act as mere cognitive enhancers that give a temporary boost to cognition, while being toxic to supertoxic. They cause more damage than good and the damaging effects. They are fool's nootropics. Don't be fooled by them. Some of them also cause severe dependancy and plenty of side effects. 8(
Note: Even though some nootropics cause hallucinations at high to very high doses, the deaths still doesn't exceed 200 people a year. 2C-x series is a great example.
2C-x series at low doses may have an exponential effect over time. It's one of the only chemical classes at sub-perceptual doses to work better when you're smart. Even the occasional strange thought that initially doesn't makes sense at first becomes part of the answer to some other questions. abstract thinking. %)
DMAA has stimulant properties without the cognitive damage.
Nootropics are a complex web.
http://www.youtube.com/watch?v=00gFvg2iUcY&feature=player_embedded
Nootropics are better when they are supplementary to a healthy lifestyle and good healthy food.
The awesome thing is that some psychedelics have displayed nootropic effects at sub-psychedelic doses. The 2C-x series being an example. They also inspired analogues with more tailered effects. Such as IAP(IndanylAminoPropane) being a less potent, but longer lasting version of MDA. IAP might have great anti-depressant and therapeutic potential without interfering with daily cognitive tasks. It's like some of them work in the background.
There's more information on wikipedia, smarter nootropics, the big and dandy nootropics thread (stack 2), and many other places. Just remember, you want to end up like the Eddie Morra from limitless at the end of the movie, not the beginning. In the movie, he encounters NZT-48 (a pseudonootropic that temporarily raises IQ to a 4 digit level and boosts confidence). The NZT-48 appears to cause a high dependancy, side effects(especially while off it) and is highly addictive with withdrawal symptoms and blackouts. NZT-48 just seems meth-like. In the end, he gets labs to reengineer it to take out the side effects and toxicity and no physical dependance, side effects, or withdrawal symptoms. Thus, NZT-49(a real nootropic) was born. NZT-49's effects are permanent and exponential increase in cognition. It seems like it would be like phenylpiracetam for concentration combined with a low dose of 2C-x compounds(likely 2C-D for memory enhancement and increased problem solving. A low dose of 2C-I could be stimulating.) and with DMAA(Dimethylamylamine) added for clean alertness and energy and maybe 2-methyl-2-butanol for increased confidence and sociability. NZT-48 is NZT-48(Dangerous! What did you ate?). NZT-49 is NZT-49(very benign

safe.
http://www.youtube.com/watch?v=QQi_d9c2oEs When he finally invents NZT-49.
http://www.youtube.com/watch?v=obeh_raHAUk When he didn't think to Create NZT-49, but is left with the toxic effects of NZT-48 already kicking in after only a year or so. 8(