Featured math content

Here are a few of the best pages on Ar­bital, se­lected by our ed­i­tors.

Bayes’ rule: Guide

A cus­tomiz­able multi-page ex­plo­ra­tion of one of the core con­cepts be­hind good rea­son­ing.


An ex­tended ex­plo­ra­tion of log­a­r­ithms and their var­i­ous uses.


An en­gag­ing ex­pla­na­tion of deriva­tives, suit­able for al­most ev­ery­one.

Un­countabil­ity: In­tu­itive Intro

A graph­i­cal ex­pla­na­tion un­countabil­ity, with al­ter­nate lenses for peo­ple with differ­ent math­e­mat­i­cal back­grounds.

Par­tially or­dered set

Posets and tightly re­lated con­cepts pitched for a tech­ni­cal au­di­ence, with ex­er­cises and ex­am­ples.

Rice’s Theorem

An ex­pla­na­tion of Rice’s The­o­rem and its im­pli­ca­tions, with a lens that ex­plores the con­nec­tion be­tween the the­o­rem and the halt­ing prob­lem.

Cat­e­gory theory

Var­i­ous pages on Cat­e­gory The­ory, ex­plor­ing how con­cepts from differ­ent do­mains of math­e­mat­ics share the same un­der­ly­ing struc­ture.


A handy dis­am­bigua­tion page be­tween the four differ­ent things peo­ple some­times mean when they say “bit”.


  • Mathematics

    Math­e­mat­ics is the study of num­bers and other ideal ob­jects that can be de­scribed by ax­ioms.