Identifying what is and isn't antisemitism is in the 21st century can be difficult. Whilst most people are familiar with overt and far-right forms of antisemitism, left-wing antisemitism is both increasingly common in online spaces and harder to identify. It is not uncommon for individuals who think of themselves as progressive or "anti-racist" to unconsciously hold antisemitic attitudes, and to make use of antisemitic language and tropes. 

TSP makes use of the IHRA Working Definition of Antisemitism. This is the standard international definition, and has been adopted formally by many countries and organisations including the USA, the UK, Canada, Australia and the EU.

In practical terms the kind of antisemitism that we are likely to see in NationStates comes in four forms;

Pro-Genocide Antisemitism and Holocaust Denial
This is most extreme form of antisemitism, and is most commonly expressed by far-right and Islamic-extremist antisemites. However people who hold these views can be left-wing, and these views can also be found in left-wing spaces.

Conspiratorial Antisemitism
Conspiratorial antisemitism makes use of antisemitic tropes, especially in relation to supposed Jewish power and influence. This form is often tied to anti-elite sentiment; opposition to ‘globalists’, anti-capitalism and anti-bankers politics, and often involves theories about the Rothschild family. The idea that Jewish people have undue influence on world politics and a secret agenda is an age-old trope. It is often promoted by claiming that Jewish people dominate banking and the media, or that Jewish people have deep political connections. A common trope is the idea that a Zionist or Jewish "lobby” steers or otherwise controls politics.

Anti-Israeli Antisemitism
It is common for individuals to use antisemitic language and tropes when discussing issues relating to Israel. It is not antisemitic to criticize Israel, but some criticisms of Israel are inherently antisemitic and otherwise legitimate criticisms of Israel can be expressed via antisemitc language and tropes. It is antisemitic to blame Jews as a group and individually for the policies of the Israeli state. This includes those who use and abuse the term Zionism as a term solely used as abuse of Jewish people rather than a descriptor of a broad and varied political, cultural, social, and religious ideology. Comparisons of Israel and Nazi Germany are explicitly antisemitic.

Denialism
The refusal to acknowledge the existence of antisemitism despite overwhelming evidence of it can itself be an antisemitic act. Those engaged in denialism gaslight Jews by claiming that antisemitic incidents did not occur, or that they were not antisemitic. This includes people who - whilst not otherwise displaying antisemitic behaviour - consistently deny that there is a problem with antisemitism, dismiss allegations of antisemitism as nothing more than smears, and attack those who believe there is a problem. Denialism often employs antisemitic tropes, such as suggesting that Jews have fabricated allegations of antisemitism to silence criticism of Israel or to smear a politician who would make them pay more taxes.
Antisemitism is banned from TSP - period. This is in keeping with our policies for all forms of racism, sexism, homophobia, or any other expressed forms of bigotry. Known antisemites may be pre-emptively banned from TSP. Expressions of pro-genocide antisemitism, holocaust denial, and conspiratorial antisemitism will all incur an immediate and indefinite ban from TSP.

Anti-Israeli antisemitism and denialism will not automatically incur a ban from TSP, due to the fact that these forms can be expressed unconsciously or from ignorance. Where an individual has been found to express these forms of antisemitism they will initially be referred to educational material. Should these expressions be repeated after this then warnings will be issued, and if they keep reoccurring then a ban will be imposed.

There are numerous sources of information and education about antisemitism available online. The US based Anti Defamation League (ADL) maintains a database of hate symbols whilst Britain's Campaign Against Antisemitism (CAA) has a guide to antisemitism on social media. 

Left-wing antisemitism is often harder to identify than right-wing variants. Hope Not Hate provides a brief guide to identifying and understanding left-wing antisemitism. Key resources for understanding left-wing antisemitism are That's Funny You Don't Look Anti-Semitic and Contemporary Left Antisemitism, both of which can be read for free online.

Antisemitism: Here and Now by Deborah Lipstadt is the definitive work on 21st century antisemitism but is not currently available for free online.