## What is an Expression?

**Quick answer**Expressions are combinations of symbols, variables, constants, operators and functions that evaluate (calculate) to a result or value.

An expression is a combination of symbols, variables, constants, operators, and functions that evaluate to a value or result.

You can think of expressions as mathematical statements - they take in one or more pieces of data (variables or constants) and perform operations on them to compute some kind of output.

For example, the expression `2 + 3`

evaluates to `5`

. The two numbers in this expression are called operands while the operator `+`

performs the addition operation.

Some other common operators are subtraction (`-`

), multiplication (`*`

), division (`/`

), and modulus (`%`

, which returns the remainder after division).

So in essence, an expression is like a tiny computer program - it takes in input and performs some kind of computation on it to produce an output.

## Different Types of Expressions

Expressions come in many shapes and sizes.

Some are simple like `x + 2`

. Others can involve more complicated operations such as function calls with multiple parameters: `Math.max(x1, x2)`

.

Generally speaking, there are three main types of expressions: arithmetic expressions, logical expressions, and functional expressions.

### Arithmetic Expressions

Arithmetic expressions are used to perform calculations involving numbers using basic math operators such as addition (+), subtraction (-), multiplication (*), division (/) and others.

They usually include two operands (e.g., 5 + 2) but could also include multiple operands in certain cases (e.g., 5 + 2 + 8). The result of evaluating an arithmetic expression typically depends upon the values held by its operands as well as their corresponding operator type (i.e., addition vs multiplication).

### Logical Expressions

Logical expressions involve comparison operators such as equal-to (==), not-equal-to (!=), greater-than (>=), less-than (<=), and others.

These operators allow you compare two values stored within variables or constants for truthiness - that is if they represent true or false statements based on particular conditions set by your program's logic flow/structure.

For example, you might write a conditional statement like: `if x >= y then do something`

, which would only activite if "x" is indeed greater than or equal to "y".

### Functional Expressions

Functional expressions employ functions - pieces of code that take arguments from caller functions/procedures and return a value based on those arguments' values combined with other built-in logic present within the function body itself.

Common examples include:

- string manipulation functions such as substr() and trim()
- math functions such as min() and max()
- looping structures such as foreach() , map() and filter().

Each of these has its own purpose depending upon what you're trying to accomplish with your program/application's end goal in mind