There are 3 main types of attraction you need to know about:

Sexual Attraction:
Sexual attraction is attraction based on sexual feelings or sexual interest towards another person. Sexual attraction aligns with someone’s sexual orientation, ie. if someone is heterosexual they will be sexually attracted to the opposite sex. 

Romantic Attraction:
Romantic attraction is attraction based on romantic feelings or interest towards another person. Romantic attraction may or may not align with someone’s sexual attraction - for example, someone may be asexual and bi-romantic, or homosexual and aromantic. 

Aesthetic Attraction:
Aesthetic attraction is attraction based on another person’s appearance in terms of aesthetic pleasure, ie. finding someone good looking in an objective way. It is sometimes conflated with sexual attraction - however, aesthetic attraction is not sexual or romantic in nature, as it is possible to aesthetically appreciate someone without being sexually/romantically attracted to them.

Note: There are more types of attraction (e.g. sensual, queer platonic) than listed here, and sometimes different types of attraction can be difficult to distinguish from each other. For most people, their romantic and sexual attraction align  perfectly - however, this is not the case for everyone, particularly those on the ace- or aro-spectrums.

There are different types of romantic orientations, just like there are different types of sexual orientations. This is because romantic and sexual attractions do not always align.

Aromantic
A person who is not romantically attracted to any gender. 

Homoromantic
A person who is romantically attracted to the same sex. 

Heteroromantic 
A person who is romantically attracted to the opposite sex.

Biromantic
A person who is romantically attracted to two or more genders.

Panromantic 
A person who is romantically attracted to people regardless of gender.

What does it mean if a woman is a lesbian?

A lesbian is a homosexual woman. She feels sexual attraction to people of the same sex as herself. Someone who is lesbian is only attracted to people of the same sex.

My friend came out as lesbian what do I do?

Treat them as normal, nothing about who they are as a person has changed.

Misconceptions you may have that you need to challenge;

You need to understand that people who are lesbian have a preference, or type in the same way a straight person does, they are not attracted to every person of the same sex who walks the earth.

T/w - the following paragraph mentions sexual assault

People who are lesbian are not broken, and having intercourse with the opposite sex will not "fix" them, it can be traumatising for people of the opposite sex to force themselves on lesbians and doing so is rape.

Skip to here to avoid mentions of sexual assault.

Having consenting intercourse with people of the opposite sex does not invalidate a lesbian's sexual orientation, it can take time to work out your sexual orientation, whatever it may be.

Why may some women who are only attracted to the same sex not identify as lesbian?

They may not feel comfortable with the term due to the unfortunate association with pornography that has been developed for generally straight, male audiences.

Please remember;
Lesbian is not a dirty word.

What does it mean if someone is gay?

The term gay can be used as an umbrella term to describe anyone whose sexual orientation is not heterosexual.

In this infopage we will be referring to gay as describing homosexual men, men who are attracted to the same sex.

My Friend came out as gay what do I do?

Treat them as normal, nothing about who they are as a person has changed.

Misconceptions you may have that you need to challenge;

You need to understand that people who are gay have a preference, or type in the same way a straight person does, they are not attracted to every person of the same sex who walks the earth.

T/w - the following paragraph mentions sexual assault

People who are gay are not broken, and having intercourse with the opposite sex will not "fix" them, it can be traumatising for people of the opposite sex to force themselves on gay men and doing so is rape.

Skip to here to avoid mentions of sexual assault.

Having consenting intercourse with people of the opposite sex does not invalidate a gay man's sexual orientation, it can take time to work out your sexual orientation, whatever it may be.

What does it mean to be bisexual?

Someone who is Bisexual is attracted to two or more genders.

Bisexuality is a very diverse sexual orientation and people within the Bisexual community may define it in different ways as it may mean different things for different people.

My Friend came out as Bi what do I do?

Treat them as normal, nothing about who they are as a person has changed.

If they are comfortable with talking about it to you, you can ask them what their Bisexuality means for them.

You need to understand that people who are Bisexual may have a preference, or may not, it does depend on the person.

People who are Bi are not greedy, and statistically speaking, being Bisexual certainly does not make them more likely to cheat.

And no, being Bi doesn't mean that they have a crush on you or your friends, just like straight people do not feel attracted to everyone of the opposite sex, Bisexuals do not feel attracted to everyone of the same/opposite sex.

What does it mean if someone is asexual?

Asexuality is where someone does not experience sexual attraction.

What asexuality is not;

A disorder or sexual dysfunction

A mental health condition

Unnatural

Something someone "will grow out of".

My partner has come out as asexual what does this mean what do I do?

First off, they're still the person you've always known.
You need to sit down and talk to them about boundaries, what they are comfortable with in terms of sexual or romantic activities ranging from hugs and kisses to intercourse.

Boundaries are important in any relationship and with people who are asexual it is especially important to keep in mind that boundaries can change day to day.

What was okay yesterday won't necessarily be okay today.
^^^this is important for everyone to consider regardless of sexuality.

Communicating about intimacy is important in any healthy relationship but especially important if your partner is asexual.

What does it mean if someone is demisexual (sometimes shortened to demi)?

Demisexuality is where someone does not experience sexual attraction until they have formed a deep emotional connection to a person.

Demisexuality sits under the umbrella of asexuality but is not the same.

What demisexuality is not;

Not having found the right person yet

A mental health condition

Unnatural

Something someone "will grow out of"

Childish.

My Friend has come out as Demi, what do I do?

Do not treat them any differently, they are still the same person.

Do not try to "hook them up" with people you think they would like if they have explicitly said no, whatever someone's sexual orientation is this is generally just rude and borderline intrusive.

Do not show them different people or go through people you both know going; "how about them? No? What about-"
If you do this, maybe go reread our definition.

My partner has come out as Demi what does this mean, what do I do?

First off, they're still the person you've always known.
You need to sit down and talk to them about boundaries, what they are comfortable with in terms of sexual or romantic activities ranging from hugs and kisses to intercourse.

Boundaries are important in any relationship!

Communicating about intimacy is important in any healthy relationship.

If someone is cisgender their gender identity matches the biological sex they were assigned at birth.

E.g.
Katy was assigned female at birth and her gender identity is female, this means her gender identity and sex assigned at birth match. Katy is cisgender.

The word cisgender is regarded as the opposite of the word transgender.

What does it mean if someone is transgender?

Currently if someone is born with
'male reproductive organs' (a penis etc),
they are assigned male at birth (AMAB for short)
and if someone is born with
'Female reproductive organs' (a vagina etc),
They are assigned female at birth,
Or AFAB for short.

Cisgender people's gender identity matches their sex assigned at birth.
Transgender people's sex assigned at birth does not correspond to their gender identity.

What does it mean if a man is a transgender man?

A transgender man is a man who's sex was assigned female at birth, but who's gender is male. His transition would be referred to as Female to Male (FTM).

What does it mean if a woman is a transgender woman?

A transgender woman is a woman who's sex was assigned male at birth, but who's gender is female. Her transition would be referred to as Male to Female (MTF).

My friend or relative has come out as trans to me what do I do?

Ask their pronouns and their name, remember them.
When you think of them try to use their correct name and the pronouns they told you to use.
E.g
Situation; My friend Kaleb tells me they are trans, that their pronouns are she/her and that she wants to be known as Kayla.

*I see something at the store
- I actively think, Oh, Kayla would love this it's just her colour!

This way you are not outing Kayla to anyone but you are also ingraining her name and pronouns into your memory, helping you associate her name with her face quicker.

Here's a short list of what you cannot ask anyone who is transgender and why it's inappropriate to do so;

- Do not ask about sexual reassignment surgery or hormone replacement therapy unless they have told YOU PERSONALLY they are comfortable talking about it with YOU.
Why?
It's none of your business, people don't ask you about e.g "what's in your pants" why would you ask them? It is highly intrusive.

- Do not ask if they have had "The" surgery, there are many different types of surgeries that trans people can have. Some people may alsl choose not to have surgeries, for medical, financial or personal reasons.
Why?
Again, what surgeries/hormones they may or may not have/take or want to have/take it is not really anything to do with you. Also, it's again intrusive and inappropriate.

-Don't ask "when they became trans" they didn't become trans, they always were trans, an inaccurate comparison would be that in the same way no one becomes gay, no one "becomes" trans.
Why?
It's inappropriate, rude and invalidating.

What is non binary defined as?

As an umbrella term it is used by individuals who experience their gender as exclusively male or female, it can be a mixture of the two or maybe something completely outside those binaries.
Here it may help to think of gender as a colourwheel, with male being blue and female being red, the term non-binary encapsulates any identity that is not that red or that blue.

What does it mean?

It can mean many different things to different people, if a close friend comes out and feels comfortable talking about this with you, you can ask them what being non-binary means to them.

My friend just came out as non-binary (aka enby or nb), what do I do?

Great question,
start by asking their pronouns.
Non-binary people do not always use they/them pronouns, they can ask any they feel comfortable with!

If you are unsure of someone's pronouns though, they/them is a great place to start since they are neutral.

Remember they're still your friend and this doesn't mean they've changed who they are, it just means they feel comfortable with showing you their authentic selves.

Please remember; non-binary people can use any pronouns and do not have to present androgynously

The way that they express themselves does not invalidate their identity and how they express themselves is never an excuse to invalidate their identity.