Good Computer Science answers use the exact term and pair it with a clear example. This glossary covers sixteen terms that learners often swap, each with its confusing neighbour.
Learn the English term first, since the exam is in English. The concept bridge tool shows the Bahasa Melayu and Chinese ideas next to it. The full topic map is in the learning guide.
Data and numbers
1. Bit and byte. A bit is one binary digit, 0 or 1. A byte is a group of 8 bits. Example: the number 13 needs 4 bits (1101), but it is usually stored in one byte (00001101). Confused with: each other. See representing numbers and text.
2. Binary and hexadecimal. Binary uses base 2, hexadecimal uses base 16 (digits 0 to 9 and A to F). Example: binary 1111 0000 is hexadecimal F0. Hexadecimal is a shorter way to write binary, not a different kind of data. Confused with: denary, which is ordinary base 10.
3. Lossy and lossless compression. Lossless keeps every bit so the original can be rebuilt exactly. Lossy removes data that cannot be recovered. Example: a zipped text file is lossless, because a missing letter would change the text. Confused with: file size reduction in general. See images, sound and storage.
4. Parity bit and checksum. A parity bit is one extra bit that makes the count of 1s even or odd. A checksum is a value calculated from a block of data and sent with it. Example: 1011001 has four 1s, so an even parity bit is 0. Confused with: encryption, which hides data rather than checks it. See data transmission and checking.
Hardware and software
5. RAM and ROM. RAM holds data and programs currently in use and is cleared when power is lost. ROM holds start-up instructions and keeps them. Example: the computer’s start-up program sits in ROM, your open document sits in RAM. Confused with: storage such as an SSD. See hardware and processing.
6. Compiler and interpreter. A compiler translates the whole program into machine code before it runs. An interpreter translates and runs it one line at a time. Example: an error found on line 40 by an interpreter may appear only after lines 1 to 39 have already run. See software and systems.
7. Logic gate and truth table. A gate is a component that outputs 1 or 0 from its inputs. A truth table lists every input combination and the output. Example: an AND gate outputs 1 only if both inputs are 1. See Boolean logic.
Programming and testing
8. Variable and constant. A variable can change while the program runs. A constant is set once and does not change. Example: Pi ← 3.14 as a constant, Total as a variable.
9. Selection and iteration. Selection chooses between paths (IF). Iteration repeats steps (loops). Example: checking whether a mark passes is selection, adding every mark is iteration. See repetition and arrays.
10. Procedure and function. Both are named blocks of code. A function returns a value, a procedure does not. Example: a function that returns the larger of two numbers, a procedure that prints a menu. See programming structure.
11. Syntax error and logic error. A syntax error breaks the rules of the language, so the program will not run. A logic error runs but gives a wrong result. Example: writing Total ← Total - i when you meant + is a logic error. See validation, verification and testing.
12. Validation and verification. Validation checks that data is reasonable, for example an age between 0 and 120. Verification checks that data was entered or copied correctly, for example typing a password twice. Example: a valid but wrong age, 35 instead of 53, passes validation, and only a verification step such as typing it twice can catch it.
13. Test data types. Normal data is valid and typical. Boundary data is at the edge of what is allowed. Abnormal data should be rejected. Example: for ages 13 to 18, test 15 (normal), 13 and 18 (boundary), 12, 19 and “abc” (rejected).
Databases and security
14. Primary key and foreign key. A primary key identifies each record in its own table. A foreign key is a field that holds another table’s primary key to link them. Example: StudentID is the primary key in Students and a foreign key in Results. See databases and query reasoning.
15. AND and OR in a query. AND needs both conditions true, OR needs at least one. Example: Year = 10 AND Club = "Chess" returns fewer rows than Year = 10 OR Club = "Chess".
16. Encryption and hashing. Encryption scrambles data so the right key can unscramble it. Hashing turns data into a fixed value that is not meant to be reversed. Example: encryption protects a message in transit. See internet, security and responsible use.
How to use this list
Pick four pairs a week. For each pair, write one sentence saying what is different, then make up your own example. If you cannot, add it to your mistake log.
Then test yourself with mixed questions in original practice. If the wrong-word habit persists, online one-to-one Computer Science tuition starts with a paid one-hour trial at the assigned teacher’s confirmed rate, from RM80.