ASCII (American Standard Code for Information Interchange) characters are a set of standardized numeric codes that represent characters used in computers and electronic communication. Here's a brief overview of ASCII characters:

1. Printable Characters: These are the standard characters that can be printed and displayed. They include uppercase and lowercase letters, digits, punctuation marks, and special symbols such as @, #, $, %, etc.

2. Control Characters: These are non-printable characters used to control peripheral devices such as printers and terminals. Examples include carriage return (CR), line feed (LF), tab (TAB), and escape (ESC).

3. Extended ASCII Characters: Extended ASCII characters are additional characters beyond the standard ASCII set, typically used for specific languages or symbols. These include accented letters, currency symbols, and graphical characters.

Each ASCII character is represented by a 7-bit binary number, which allows for a total of 128 (2^7) possible characters. The ASCII standard has been extended to include additional characters and variations, leading to standards such as ISO 8859 and UTF-8, which support a wider range of characters and languages.

Here are some examples of ASCII characters:

- Uppercase letters: A, B, C, …, Z - Lowercase letters: a, b, c, …, z - Digits: 0, 1, 2, …, 9 - Punctuation marks: ! “ # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { | } ~ - Control characters: CR (carriage return), LF (line feed), TAB (tab), ESC (escape), etc.

It's important to note that ASCII characters are limited to the English alphabet and basic symbols. For languages with different character sets, other encoding standards like Unicode are used.