数学上，不等是表明两个对象的大小或者顺序的二元关系（参见等于）。不等关系主要有四种：

上述两个属于严格不等。

将两个表达式用不等符号连起来，就构成了不等式。

若不等关系对变量的所有元素都成立，则称其为“绝对的”或“无条件的”。若不等关系只对变量的部分取值成立，而对另一部分将改变方向或失效，则称为条件不等。

不等式两边同时加或减相同的数，或者两边同时乘以或除以同一个正数，不等关系不变。不等式两边同时乘以或除以同一个负数，不等关系改变方向。

符号 a >> b 表示 a “远大于” b。其含义是不确定的，可以是 100 倍的差异，也可能是 10 个数量级的差异。和方程相联系，它被用来给出一个非常大的值而使方程的输出满足一个特定的结果。

Not to be confused with Inequation. "Less than" and "Greater than" redirect here. For the use of the "<" and ">" signs as punctuation, see Bracket. For the UK insurance brand "More Th>n", see More Than (company).

In mathematics, an inequality is a relation that holds between two values when they are different (see also: equality).

If the values in question are elements of an ordered set, such as the integers or the real numbers, they can be compared in size.

In contrast to strict inequalities, there are two types of inequality relations that are not strict: