Why Tall or Wide?

NEWBIE Question:
I have played 3 or 4 games to completion and this is my first Civ game so I have a lot to learn. But why is the general principle to have a few cities with high population or many cities with lower population. I have generally expanded to get as much territory as I can early so I don't become a warmonger but get lots of resources and just make them all crank out as many buildings/population/etc until I can achieve a victory condition.

Is there something on the higher difficulties (still on lvl 4, going up one each time I win) that makes it so you have to go Tall or Wide and not just go full throttle on cities and their population? Thanks all.

I play on emperor and I find that in this game, 50% of your fight is fighting your own happy cap, rather than fighting your opponents. How are you generating your global happiness?

I know the lower difficulties give you an increased base Happiness. Plus I just spam the hell out of coloseums/courthouses/zoos as I expand.

So you see the Happy Cap as being the primary attribute to slow your expanding? Do people literally start starving cities to keep them at an appropriate level?

Happiness is the main limiter to growth and expanding yes. If you had unlimited happiness then yes you'd expand as much as possible and grow each individual cities as tall as possible.

If the point of the original question was why not a medium number of medium sized cities, the answer is probably that this would not get maximum value from either tradition or liberty social policy trees.

On higher levels, real estate is another contributing factor. Deity AI start with 2 settlers at turn 0 and have crazy bonuses to production, so they'll often fill in some of the city sites you want before you can get there. Especially when they don't like you and/or want to start a war with you, in which case they'll make an additional settler to plant a city lust outside your borders as a base of operations for their assault on you.

@Badx2

Have a look at the War Academy. There are lots of useful articles there:

http://forums.civfanatics.com/forumdisplay.php?f=451

'Tall or Wide' is nothing more than general strategy.
It originates from social policies - if you take tradition, you really want your cap big to gain bonus from Monarchy, also since you have +%food - you want to focus on food. If you focus on food and still have much excess happiness - settle more.

If you take liberty - you have small +% production and you do not have any food bonuses, also you have cheap settlers and happiness for each city. Quite obvious you want to mass cities.

Reasons to self build Tall:
1. It's suitable as every civ in every situation.
(There are situations in which self founding wide won't work at all:
Insufficient local luxury diversity of resources (happiness issues for wide due to AI being tardy connecting its spare luxuries)
Started too close to multiple AIs with high expansion flavors (AI took the good cities before you)
Started to close to a highly aggressive AI (a military was more important)
Or playing as Venice where you aren't allowed to build settlers at all

2. Tradition policies include massive growth and happiness bonuses. (Free Aqueducts with G&K and BNW in addition to global food bonuses), Monarchy knocks 50% of the population unhappiness from the capital (and gives more gold from population in capital). In addition Tradition has another happiness policy that makes every 10th citizen in a given city unhappiness free.

3. You can easily attach a wide empire to a tall core via 3 or 4 city Tradition first and war mongling later, timing any annexations to be when they won't interfere with national wonder construction.

4. Time to victory is so short that self built wide empires can't really compete in terms of fewest turns to victory.