This page explains how to place various mathematical characters into HTML documents. A 1999 version of this document is available here and a 2005 version here. The symbols have been grouped into the following categories:
| Operation Symbols | 
| Relation Symbols | 
| Arrows and Brackets | 
| Greek Symbols | 
| Miscellaneous Symbols | 
Update (1 Sep 2009): In this version the Symbol FONT FACE TAG method has been eliminated because they are no longer reliable.
Update (19 Mar 2007): Additional character entities
INTRODUCTION
There are several ways to add these symbols to your pages.  I will omit consideration of symbols which appear on the keyboard unless, like &, they have a special HTML meaning.  Of course, for any symbol, a .gif image can be created and the image displayed using the <img> tag.  I will omit consideration of this strategy as well.  In the tables below two codes will be given for displaying a character: the HTML numerical code and a special HTML literal code (where available).
One more thing. To form superscripts or subscripts use the <SUP> or <SUB> tags.
BROWSER TEST: To view symbols with numeric codes above 255 and perhaps some literal code symbols the browser character encoding must be set to unicode (UTF-8). 
If the following string of symbols cannot be read, the browser setting needs to be changed. 
Upwards arrow (Numeric code: ↑, Literal code: ↑), intersection (Numeric code: ∩, Literal code: ∩)
| NAME | SYMBOL | NUMERIC CODE | LITERAL CODE | 
|---|---|---|---|
| For all | ∀ | ∀ | |
| There exist | ∃ | ∃ | |
| Not | ¬ | ¬ | |
| And (meet) | ∧ | ∧ | |
| Or (join) | ∨ | ∨ | |
| Intersection | ∩ | ∩ | |
| Union | ∪ | ∪ | |
| Plus or minus | ± | ± | |
| Times | × | × | |
| Partial derivative | ∂ | ∂ | |
| Solid dot | ∙ | None | |
| Middle dot | · | · | |
| Circle times | ⊗ | ⊗ | |
| Circle plus | ⊕ | ⊕ | |
| Division | ÷ | ÷ | |
| Big product | ∏ | ∏ | |
| Big sum | ∑ | ∑ | |
| Square root | √ | √ | |
| Integral | ∫ | ∫ | 
| NAME | SYMBOL | NUMERIC CODE | LITERAL CODE | 
|---|---|---|---|
| Contains the element | ∍ | None | |
| Is a member of | ∈ | ∈ | |
| Is not a member of | ∉ | ∉ | |
| Less than | < | < | |
| Greater than | > | > | |
| Isomorphism | ≅ | ≅ | |
| Perpendicular | ⊥ | ⊥ | |
| Vertical bar | | | None | |
| Less than or equal | ≤ | ≤ | |
| Greater than or equal | ≥ | ≥ | |
| Not equal to | ≠ | ≠ | |
| Equivalent to | ≡ | ≡ | |
| Approximately | ≈ | ≈ | |
| Similar to | ∼ | ∼ | |
| Empty set | ∅ | ∅ | |
| Contains properly | ⊃ | ⊃ | |
| Contains | ⊇ | ⊇ | |
| Not included in | ⊄ | ⊄ | |
| Proper subset of | ⊂ | ⊂ | |
| Subset of | ⊆ | ⊆ | 
| NAME | SYMBOL | NUMERIC CODE | LITERAL CODE | 
|---|---|---|---|
| Left brace | [ | None | |
| Right brace | ] | None | |
| Left angle bracket | < | None | |
| Right angle bracket | > | None | |
| Left curley bracket | { | None | |
| Right curley bracket | } | None | |
| Double arrow | ↔ | ↔ | |
| Left arrow | ← | ← | |
| Up arrow | ↑ | ↑ | |
| Right arrow | → | → | |
| Down arrow | ↓ | ↓ | |
| Double big arrow | ⇔ | ⇔ | |
| Double left arrow | ⇐ | ⇐ | |
| Double up arrow | ⇑ | ⇑ | |
| Double right arrow | ⇒ | ⇒ | |
| Double down arrow | ⇓ | ⇓ | |
| Ellipsis | … | … | |
| Left angle quote | « | « | |
| Right angle quote | » | » | 
| NAME | SYMBOL | NUMERIC CODE | LITERAL CODE | 
|---|---|---|---|
| alpha | α | α | beta | β | β | gamma | γ | γ | delta | δ | δ | epsilon | ε | ε | zeta | ζ | ζ | eta | η | η | theta | θ | θ | iota | ι | ι | kappa | κ | κ | lambda | λ | λ | mu | μ | μ | nu | ν | ν | xi | ξ | ξ | omicron | ο | ο | pi | π | π | rho | ρ | ρ | sigma | σ | σ | tau | τ | τ | upsilon | υ | υ | phi | φ | φ | chi | χ | χ | psi | ψ | ψ | omega | ω | ω | 
| NAME | SYMBOL | NUMERIC CODE | LITERAL CODE | 
|---|---|---|---|
| Blank space | None |   | |
| Number sign | # | None | |
| Percent | % | None | |
| Ampersand | & | & | |
| Prime | ′ | ′ | |
| Double prime | ″ | ″ | |
| Quote | None | " | |
| Therefore | ∴ | ∴ | |
| Overline | ‾ | ‾ | |
| Infinity | ∞ | ∞ | |
| Degree | ° | ° | |
| Long dash | — | — | |
| Aleph | ℵ | ℵ | |
| Angle sign | ∠ | ∠ | |
| Upside-down triangle | ∇ | ∇ | |
| One-half | ½ | ½ | |
| Cent sign | ¢ | ¢ | |
| Registered sign | ® | ® | |
| Copyright sign | © | © | |
| Trademark sign | ™ | ™ |