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Morse Code
International Morse code: the alphabet, timing, prosigns, history and how to learn it by ear.
Does Anyone Still Use Morse Code?
Yes. Amateur radio operators use Morse code daily, the FCC dropped the US exam requirement in 2007, and Gboard added Morse input for accessibility in 2018.
History of Morse Code
Morse code was invented by Samuel Morse and Alfred Vail in the 1830s. Learn how it went from the first telegraph line to a global standard still in use today.
How to Learn Morse Code
Learn Morse code in weeks using the Koch method: start at full speed with two characters, add more as you hit 90% accuracy. No memorizing charts needed.
How to Type Morse Code on Your Phone
Enable Morse in Gboard on Android via Settings, Languages and input. On iPhone, add Morse Code (US) in the Gboard app. Dots and dashes type real text.
International vs. American Morse Code
International Morse uses only dots and dashes. American Morse had three mark lengths and different encodings. International became the global standard.
Morse Code for Kids
Morse code uses dots and dashes for every letter. Start with SOS (· · · — — — · · ·) and your name, then practice tapping on a desk or flashing a light.
Morse Code Prosigns and Abbreviations
Morse prosigns are sent without letter gaps: AR ends a message, SK ends a contact, BT is a break. Q-codes and common CW abbreviations included.
Morse Code Timing Explained
Morse code timing follows four ITU rules: a dash is 3 dots long, gaps within a letter are 1 dot, between letters 3 dots, and between words 7 dots.
Morse Code with Light and Sound
Send Morse code with a flashlight or buzzer. Short = dot, long = dash (3x). Letter gap = 3 units, word gap = 7 units. SOS step-by-step included.
SOS Meaning and History
SOS does not stand for anything. It is a Morse prosign (· · · — — — · · ·) adopted at the 1906 Berlin conference and effective internationally on 1 July 1908.
Binary & Computer Codes
Binary, hexadecimal, ASCII, UTF-8 and Base64 — how computers turn text into numbers and back.
ASCII vs. Unicode: What's the Difference?
ASCII covers 128 characters for English. Unicode covers over 149,000 characters for every human writing system. UTF-8 encodes both and is the web standard.
Binary vs. Hexadecimal: What's the Difference?
Binary uses base 2 (digits 0–1); hex uses base 16 (digits 0–9 and A–F). One hex digit equals exactly 4 binary digits, making hex a compact shorthand.
Bits and Bytes Explained
A bit is a single 0 or 1. A byte is 8 bits and holds one character. A megabyte is about one million bytes. Here is how the units stack up.
How to Convert Decimal to Binary
Divide by 2 repeatedly and read remainders bottom-up. Decimal 25 becomes 11001, decimal 100 becomes 1100100. Full step-by-step method inside.
How to Read Binary Numbers
Binary uses only 0 and 1. Each digit is a power of 2, so 01000001 = 65 = the letter A. Learn to decode any binary string in minutes.
What Is Base64 Encoding?
Base64 converts binary data to text using 64 printable characters. 'Man' encodes to 'TWFu'. It is used in email attachments, data URIs, and JWTs.
What Is UTF-8? Encoding Explained
UTF-8 encodes any Unicode character as 1 to 4 bytes. ASCII uses 1 byte; é uses 2 bytes (C3 A9); emoji use 4 bytes. It is the encoding of the modern web.
Braille
Unified English Braille: the six-dot cell, letters, numbers, capital signs and how grade 1 and grade 2 differ.
Grade 1 vs. Grade 2 Braille: What's the Difference?
Grade 1 braille is letter-for-letter. Grade 2 adds 180+ contractions to speed reading and save space. Most published braille uses Grade 2.
History of Braille
Louis Braille invented his dot system in 1824 at age 15. It was officially adopted in France in 1854 and worldwide through the 20th century.
How Braille Works
Braille uses a 2×3 grid of raised dots called a cell. Each cell pattern stands for a letter, number, or symbol. There are 64 possible patterns in all.
NATO Phonetic Alphabet
The ICAO/NATO spelling alphabet from Alfa to Zulu, its history and how to use it on the phone or radio.
How to Spell Your Name Over the Phone
Say each letter as a NATO word: A = Alfa, B = Bravo, C = Charlie. So 'Smith' becomes Sierra, Mike, India, Tango, Hotel. Works for any name, address, or code.
NATO Phonetic Alphabet History
The NATO phonetic alphabet, Alfa through Zulu, became effective 1 March 1956, based on ICAO Annex 10, replacing earlier Allied alphabets from WWII.
Roman Numerals
How to read and write Roman numerals, from I to MMMCMXCIX, including years and dates.
How to Read Roman Numerals
Roman numerals use 7 letters: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Add values left to right; subtract when a smaller value comes before a larger one.
Roman Numerals for Years and Dates
To write a year in Roman numerals, break it into thousands, hundreds, tens, and ones. 2026 = MMXXVI. 1999 = MCMXCIX. Common on films, buildings, and broadcasts.
Why Roman Numerals Have No Zero
Roman numerals have no zero because they are additive, not positional. Zero is only needed as a placeholder in place-value systems like decimal notation.
Ciphers
Caesar, Vigenère, Atbash and A1Z26 ciphers explained, with tools to encode, decode and crack them.
Caesar Cipher Explained
A Caesar cipher shifts every letter by a fixed number. HELLO with shift 3 becomes KHOOR. Julius Caesar used this cipher for military messages.
Code vs. Cipher: What Is the Difference?
A code replaces whole words with agreed symbols. A cipher transforms every letter by a rule. Morse code is technically a code; Caesar is a cipher.
Easy Ciphers for Kids
Five simple ciphers kids can use without a computer: Caesar shift, A1Z26 (A=1), reverse alphabet, pigpen, and the rail fence.
How to Crack a Caesar Cipher
Two methods crack a Caesar cipher: try all 25 shifts (brute force) or use frequency analysis — E appears in 12.7% of English text.
Vigenère Cipher Explained
The Vigenère cipher uses a keyword to change the shift for each letter. HELLO encrypted with key KEY becomes RIJVS. Much harder to crack than Caesar.