# Creating expressions

An expression is a sentence that follows a predefined syntax and that can be evaluated to return a value.

Expressions can be separated by , or ;. For example: string1 = "Hello ", string2 = "World!", string3 = concat(string1,string2).

### In this section

* [Assignment expressions](https://help.qlik.com/talend/en-US/data-shaping-language-reference-guide/8.0/assignment-expressions)
* [Operator expressions](https://help.qlik.com/talend/en-US/data-shaping-language-reference-guide/8.0/operator-expressions)
* [Conditional expressions](https://help.qlik.com/talend/en-US/data-shaping-language-reference-guide/8.0/conditional-expressions)
* [Calling Java functions in expressions](https://help.qlik.com/talend/en-US/data-shaping-language-reference-guide/8.0/calling-java-functions)