Answer:

To store a single character in Java, the data type used is char.

Explanation:
In Java, the char data type is used to represent a single character. It is a primitive data type and is 16 bits in size. The char data type can store any character from the Unicode character set, which includes characters from various languages and symbols.

Characteristics of the char data type:

1. Size: The char data type is 16 bits in size, which means it can store values from 0 to 65535.

2. Syntax: The char data type is declared using the keyword char followed by the variable name. For example, char myChar;

3. Initialization: A char variable can be initialized with a single character enclosed in single quotes. For example, char myChar = 'A';

4. Escape Sequences: The char data type also supports escape sequences to represent special characters. For example, '\n' represents a newline character.

5. Unicode Representation: The char data type uses the Unicode character set, which allows it to represent characters from different languages and symbols. Unicode is an international standard that assigns a unique number to every character.

Example:

Here is an example of declaring and initializing a char variable in Java:

```
char myChar = 'A';
```

In this example, the variable myChar is declared as a char and assigned the value 'A'. The variable can now be used to store and manipulate a single character in Java.

Conclusion:

In Java, the char data type is used to store a single character. It is a 16-bit primitive data type that can represent characters from the Unicode character set. The char data type is widely used in Java programs for various purposes such as storing letters, symbols, and special characters.