What is in this wing

Nine pages, and they are deliberately different sizes, because the sets themselves are different sizes.

• Inequality symbols — 90 comparison characters. The two you came for are ≤ and ≥; the page also separates the three different characters that all read "less than or equal to".
• Set theory symbols — 90 characters for membership, containment and combination: ∈, ∪, ∩, ∅ and the long tail of variants.
• Logic symbols — 37 characters, the quantifiers and connectives plus the turnstiles.
• Math symbols — 87 operators, the general list: arithmetic, calculus, the n-ary operators.
• Greek letter symbols and Greek alphabet symbols — the same 56-character alphabet, approached from two directions: one as symbols used in formulae, one as an alphabet.
• Exponent and index symbols — 32 superscripts and subscripts, digits and a few signs, as single characters.
• Degree symbol — 9 characters. Small because that is all there is: the degree sign, the primes, and the two precomposed temperature signs.
• The infinity symbol — 5 characters, of which one is the one anybody wants.

A letter and an operator can look identical

Σ is U+03A3 GREEK CAPITAL LETTER SIGMA, general category Lu, an upper-case letter. ∑ is U+2211 N-ARY SUMMATION, general category Sm, a maths symbol. They can be drawn near enough alike to fool the eye and they behave differently everywhere it counts: a spell checker reads one as a letter, a case-folding routine lower-cases one and not the other, and a sort puts them in different places. The same trap sits under Π and ∏, and under any Greek letter that has an operator twin. Reach for the letter when you mean a variable and the operator when you mean an operation.

Two characters in this wing are dangerous in HTML

The inequality set includes < U+003C and > U+003E. Pasted into HTML source they open and close a tag, so a formula typed raw can eat the rest of the line. Write < and >, and use ≤, ≥ and ≠ for the rest.

Alignment in monospace

East Asian Width decides cell count in a fixed-width layout, and the maths sets are mixed. Of the 90 inequality characters, 14 are Ambiguous and 74 are Neutral; in a terminal set to render Ambiguous as double-width, ≤ takes two cells and ≲ takes one. A hand-aligned table of comparisons will drift. All 24 Greek capitals from U+0391 to U+03A9 are Ambiguous, so the same applies to a column of variables.

The other two wings are music symbols and the general symbol reference; the index has a sample of everything.