TERF

Trans-Exclusionary Radical Feminists, or TERFs are transphobes who justify their transphobia under the guise of feminism. TERFs are known for hatred of trans women particularly.

TERFs often prey on young, uneducated gay people (particularly lesbians) to indoctrinate them into their ideology. Because of this there is a large age discrepancy in TERF groups. Older TERFs (usually around their 30s) have been kicked out of local real life LGBT+ spaces due to their transphobia, so they turn to the internet to spread their bigotry. They often target young (around 12-15) lesbians who likely do not have access to real life LGBT+ spaces, and are therefore less educated on LGBT issues and are easier to manipulate. To those not familiar with TERF ideology it can be difficult to spot it, as TERF mask their bigotry with the guise of feminism. They will often make statements about "men", if one did not know that person is a TERF one would not assume that statement actually meant trans women. By hiding what they're actually saying, behind more innocuous statements they can get people to agree with them and from their can indoctrinate them into their way of thinking.

Transphobia
TERFs main doctrine is that trans people do not exist. They believe that trans women are actually men who are trying to invade women's spaces and that trans men are actually confused lesbians.

Obsession with "Biology"
Related to the previous point TERFs equate women with their genitals and believe that women that those with vaginas and uteri, and more recently, those with XX chromosomes. As such TERFs will frequently use symbols of a vagina or uterus to represent women. They also obsess over biological processes such a periods and the ability to give birth. They sometimes refer to cis women as "womben" (a combination of women and womb).

Similarly they sometimes use the word "womyn". This alternate spelling was originally meant as a way to avoid the suffix 'man'. However it was adopted by TERFs to mean cis women. TERFs also use the womyn-born-womyn (WBW) to mean "women raised as women", to exclude anyone assigned male at birth.

Hatred of Men
TERFs believe that all men are inherently oppressive and cannot change this. Trans women, and anyone assigned male at birth are included in this definition of "men". They believe that because they were born and were raise as men they are also inherently oppressive to women and cannot experience oppression due to being women.

Biphobia
Biphobia is rampant in TERF groups. Because they hate all men they believe that relationships with men (and trans women), particularly sexual relationships, are oppressive and women who willingly form relationships with men, such as straight women or bisexual women are oppressing themselves due to societal pressure. As such many TERFs are lesbians and refuse to be romantically involved with bisexual women under the belief that they've been "tainted" by men.

Sex Shaming
TERFs are also against kinky sex, believing that dom/sub interactions, even between two women, mirror the oppressive relationship between men and women. Therefore TERF ideology asserted that the only "pure" form of sex is vanilla sex between two (strictly lesbian) cis women.

Many TERFs are also sex-worker exclusionary radicial feminists, or SWERFs.

Dislike of the Word TERF
Many TERFs dislike being called TERFs as the word blatantly calls out their transphobia. Many will try to claim that TERF is a slur. They often call themselves radical feminists or rad-fems, which leaves out the trans-exclusionary part.