An inequality is a way of comparing two numbers that, well, aren't equal to each other, or aren't always equal, when talking about variables.
Greater than/less than
The number 3 is bigger than 2. We express that fact in symbols with the expression 3 > 2, which we read as "3 is greater than 2" We can express this same fact, focusing on 2 this time, with the expression 2 < 3 (2 is less than 3).
Greater than or equal to/less than or equal to
What about a statement like "it took at least 3 minutes?" In this case, we're talking about a whole range of values: anything greater than 3 minutes. But we also include the possibility that the time could equal 3 minutes. If we let t by time in minutes, we'd write that fact in symbols as t ≥ 3, and you'd read it as "t is greater than or equal to 3". The ≥ here is a mix between a > and a =, and it tells us that t could equal 3, but it could also be greater. We could also flip it to say 3 ≤ t (3 is less than or equal to t).
To summarize
- > : "Greater than" (ex: 3 > 2, "3 is greater than 2")
- < : "Less than" (ex: 2 < 3, "2 is less than 3")
- ≥ : "Greater than or equal to" (ex: x ≥ 3, "x is greater than or equal to 3", "x is at least three")
- ≤ : "Less than or equal to" (ex: t ≤ 5, "t is less than or equal to 5," "t is no more than 5")