A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
Type to find tags: 
commutativerings× 176  descriptivesettheory× 175  projectivegeometry× 175 
teaching× 175
For questions related to teaching mathematics. For questions in Mathematics Education as a scientific discipline there is also the tag mathematicseducation.

manifolds× 169  approximationtheory× 168  stablehomotopy× 165 
computationalgeometry× 164
Using computers to solve geometric problems. Questions with this tag should typically have at least one other tag indicating what sort of geometry is involved, such as ag.algebraicgeometry or mg.metr…

mathphilosophy× 162  birationalgeometry× 161  algebraicsurfaces× 159  hilbertspaces× 151 
randomwalk× 151 
riemannzetafunction× 151
the function of one complex variable $s$ defined by the series $\zeta(s) = \sum_{n \geq 1} \frac{1}{n^s}$ when $\operatorname{Re}(s)>1$. It admits a meromorphic continuati…

euclideangeometry× 150 
textbookrecommendation× 149
Questions asking for recommendations of textbooks on some subject. It can be helpful to indicate whether the request is for selfstudy, for use in a course one teaches, for use accompanying a course o…

monoidalcategories× 148  semigroups× 146 
computeralgebra× 146
Using computers to solve algebraic problems. Questions with this tag should typically include at least one other tag indicating what sort of algebraic problem is involved, such as ac.commutativealgeb…

prooftheory× 145
For question in Proof Theory, where "proofs" themselves are the object of mathematical investigation. It is not to be used to request a proof of some result.

langlandsconjectures× 142
Higher reciprocity laws

calculusofvariations× 140  groupactions× 140  zetafunctions× 139 
lfunctions× 138
Questions about generalizations of the Riemann Zeta function of arithmetic interest whose definition relies on meromorphic continuation of special kinds of Dirichlet series, such as Dirichlet Lfuncti…

differentialoperators× 136
Elliptic, parabolic and hyperbolic operators. Laplace, LaplaceBeltrami, Schrödinger, Dirac. Exterior derivative and Lie derivative operators.

convexoptimization× 136 
books× 135
Questions in which books play a keyrole, such as questions on antique books, ebooks, difference between various editions of a book, etc. For questions asking for recommendations of books on some sub…

homology× 135  universalalgebra× 135  gm.generalmathematics× 134  classfieldtheory× 127 
graphcolorings× 126  career× 125  intersectiontheory× 125  spectralgraphtheory× 124 