What is a range in poker?
The whole deck, when playing No Limit Texas Hold’em, consists of 52 cards and allows 1326 different hand-combinations. That, for example, is a 100% range as it contains every single hand-combination.
There are four suits: diamond (d), club (c), spade (s) and heart (h).
One hand-combination that you can hold is, for example, AdKs or 7h2s.
A range is simply a lot of different hand-combinations put together. Like this:
This is a top 10%-range: 77+, A9s+, KTs+, QTs+, AJo+, KQo*
This is the bottom 10%-range: 92o, 83o-82o, 73o-72o, 63o-62o, 52o, 42o+, 32o*
Why should i think in ranges? To narrow down!
The reason why you should think in ranges in poker is that you can’t put your opponent on an exact hand. As Poker is a game of incomplete information, we are better off assuming the opponents range rather than putting him on a precise hand.
The upside of putting our opponent on a range is that we can narrow his range down further and further as the betting-rounds pass by and we collect information by reading his betting patterns.
For example, if your opponent raises from the button, you call in the big blind, and the flop comes 6-7-8, and he checks. He will most certainly never have the nuts which is T9, neither will he have 66, 77, 88 or 54.
He would want to get chips with such strong holdings, and hence we can exclude these hands from his range and this is what range-reading is.
You make assumptions about your opponents play and try to narrow down ranges, optimally to a very little range including only a few combinations. That is how you can make a precise assessment and adjust your moves accordingly to it, to make a profound strategical move.
Ultimately, when having collected enough information by reading his betting-patterns, you sometimes can put your opponent on a precise hand. We can’t do that with out thinking in ranges though, in fact: Everyone thinks in ranges, some without knowing!

Equity and ranges come hand in hand
Let us build a hypothetical scenario. You only get hands dealt that are in the top 50%-range of poker-hands while your opponent only gets hands that are part of the bottom 50%-range. Now you play one VS one, and you both agree to go all-in every hand.

Your range: Top 50% range of Poker-hands

Bottom 50% range fof Poker-hands
As you can see, when ranges clashing on eachother the chance of winning fluctuates. Why is that important? The goal in Poker, when playing for financial enrichment, is to make make adjustments according to your opponents range for a higher likeliness of you winning. If you have Aces (AA) and go all-in, and someone calls with Ace King off-suited, you will have 87.86% equity. That means that you will win in 87.86 times out of 100.
Range-advantage, and why you should care about it
Every excellent Poker player not only knows what a range-advantage is but also adjusts its strategy when he or his opponent has one. A range-advantage merely means that you have favourable equity on certain runouts as you are more likely to have improved your Poker-hand. Example below:
Let’s say you open-raise and the big blind calls your raise

Your Button open-raising-range – 42%

bb defending-range vs button-raise
Let’s peak at the flop

2h-2d-2c