TRP goes through regular phases: intake of new people, education through repeated shouting of "read the sidebar" and ECs and mods getting angry in the comments, then intake of more new people.
The 'intake' phase is characterized by a proliferation of bad advice and bad theory, as newcomers start haphazardly pretending they understand things and, in so doing, reinforce each others' mistaken beliefs. The most enduring, widespread and thus indicative of these is the misunderstanding of how TRP uses the terms 'alpha' and 'beta'.
Given what I've been consistently reading over the past few weeks, it's time for us to have The Talk.
'Alpha' and 'beta' in TRP
What 'makes' you alpha? how 'are' you a beta? what should you do or say to 'be' alpha?
These questions flood the brains and posts of TRP newcomers, to be answered with imprecise and often incorrect notions derived from old-school PUA, self-improvement advice read in some god-forsaken blog, or even mainstream dating advice (eww).
If you want to have the easiest time understanding how TRP uses the terms 'alpha' and 'beta', my advice is to forget everything you think you know. I know you won't heed this advice, but later on you'll think back to this line and understand what I meant.
So, what do 'alpha' and 'beta' mean in TRP?
First of all, they refer to traits, not states of being. Traits are things like behaviors and behavioral tendencies, mind frames, physical features, social standing and so on. In a quick but imprecise way, we often talk about 'being' alpha or beta, but that simply means displaying a preponderance of alpha or beta traits in a specific situation.
Alpha traits are, by definition, those traits that engender sexual attraction, i.e. traits that make a woman want to have sex with you. They include:
Health/fitness: low body fat percentage, skin tone and clarity, physical ability (strength etc), mental ability
Masculinity: muscularity, overall body shape (V-taper etc), facial masculinity (large jaw, prominent brows, beard etc), deep voice
Dominance: confidence, steadiness, self-possession, leadership, aggression (not necessarily the violent kind)
Beta traits are, by definition, those traits that engender relationship attraction, i.e. traits that make a woman want to have a relationship with you (sex not necessarily included). Namely:
Wealth: income, assets, skills that are likely to increase your earning ability (e.g. being in medical school)
Reliability: dutifulness, truthfulness, predictability
Generosity: gift-giving, sharing of resources, sharing of time
Supportiveness: validation, patience, forgiveness
Do note an extremely important thing: while 'beta' is often used as a derisive and insulting term, beta traits are actually simply traits that favor pursuing a certain goal; it's the overabundance of beta traits and undersupply of alpha ones that creates issues, turning you into a provider doormat.
Do also note how many of these traits often mesh and merge: wealth, for example, can often come from intelligence + dominance; physical health can often derive from self-possession. It generally takes some amount of analysis to understand how each trait plays into the overall picture of a man.
Dual-mating: why we use the definitions we use
We define 'alpha' and 'beta' the way we do because it's reflective of the underlying reality of sexual dynamics, namely that women have two distinct drives when it comes to mate selection:
the drive to maximize the fitness of the offspring, by mating with a man who is healthy, masculine and dominant
the drive to associate themselves with a man who will protect and provide for them during pregnancy and child-rearing
While finding one man who covers both areas is a (literal) wet dream for most women, it is very much possible to mate with man with alpha traits (Alpha Fucks) and then cuckold a clueless provider, with plenty of beta traits (Beta Bucks). Indeed, genetic studies point to precisely such a reality: at several points in human history, nearly all women reproduced, while only a minority of men did.
The perfect fusion of alpha (reproductor) and beta (provider) traits I mentioned above is called Alpha Bucks, and as I said it's every woman's wet dream; so much so that it is universally featured in their relationship porn, such as the 50 Shades series (ultra-dominant, fit and capable billionaire who will do anything to have that special woman).
So what should I be, alpha or beta?
If you're still asking that question then you need to read more attentively.
Alpha and beta traits are traits that you can and should develop depending on your goals. However, there is a baseline of common truth here: no man wants to be sexless, hence all men need strong alpha traits. There is literally no reason not to have alpha traits and every reason to have them; hence TRP advises everyone, regardless of their situation, to lift (which develops muscularity, improves your health and generally enhances alpha traits), and in general focuses on enhancing your alpha traits.
As for beta traits, the crude reality is that you don't need them to just have sex. There are absolutely degenerate low-lives who are completely unreliable, broke and liars who still get laid like warlords because they're muscular, masculine and don't take no for an answer. There are Machiavellian assholes without a shred of kindness in their hearts who have no lack for women. Dispassionately, TRP notes that both these models work; whether that's how you want to be is your choice, but do note that while they work they're not the only ones that do, i.e. you don't need to be extreme Dark Triad to be plenty attractive.
Many traits that make you a good prospect for a relationship (i.e. beta traits, which again does not imply being a doormat pussy) often derive from well-applied alpha traits, or are desirable on their own: financial independence, for example, is a good thing for you regardless of what your goals are in life. You should certainly not rely on it, however, to generate sexual attraction.
In a committed monogamous relationship you will need a balance of alpha and beta traits; it is often described as 80% alpha 20% beta. You will need to be reasonably wealthy, reliable, generous and supportive; but all of that under the steering and direction of a healthy, masculine, dominant male core. Having only beta traits turns you into Beta Bucks and leads directly to unhappy, unfulfilling, sexless and/or cuckolded LTRs/marriages.
Finally, sexual dynamics are competitive. There isn't an absolute scale of beta and alpha: there is always someone with stronger alpha traits than you somewhere in the world, just as there is someone with stronger beta traits. This is why you don't need top grades in every category to actually get laid, even with beautiful women: don't make the mistake of countless noobs who get discouraged thinking that they'll never have a statuesque body, total self-confidence and dominance and masculinity through the roof, and thus shouldn't even try. You are competing with a pool of men who are the most effeminate, weak and unhealthy generation since the dawn of man: every improvement you make over the baseline already sets you apart and increases your chances exponentially, which is why people applying even the crumbs of TRP see immediate results; reaching the top 20% of men (which is, in truth, not that hard) will put you in such a situation of abundance as to sate most.
What you've just read is a primer, a distillate of knowledge designed for the singular purpose of dispelling mistaken notions about 'alpha' and 'beta' and setting you on the right path. It is not all that you need and, most notably, it's nearly entirely devoid of immediately actionable advice. Read the sidebar, read the archive of stickies, listen to the advice from people who've won some distinction for giving reliably good advice. Most importantly, go out there and apply what you're learning, because without application this is just a lot of mental masturbation and fantasizing. Just as you should judge women by what they do and not what they say, so you should judge yourself (and will be judged by the world) not for what you say but for what you do.