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Why everything is a number underneath, and how bits, bytes and file signatures show up in security work.
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A free account unlocks the full lesson, the five-question knowledge check, progress tracking, notes and the completion certificate.
A computer does not store letters, pictures or passwords. It stores numbers. Once you can read those numbers, a lot of security work stops feeling like magic: file signatures, hashes, permissions and network addresses all become variations on the same idea.
A bit is a single binary digit: 0 or 1. Eight bits make a byte, which gives 256 possible values (2 to the power of 8).
From there the units scale in powers of 1024, which is why a "1 TB" drive shows up as roughly 931 GB in your operating system:
Storage vendors often use powers of 1000 for marketing. Both conventions are "correct"; they are counting different things.
In decimal, each position is a power of ten. In binary, each position is a power of two.
1010 means:
| Position | 8 | 4 | 2 | 1 |
|---|---|---|---|---|
| Bit | 1 | 0 | 1 | 0 |
| Value | 8 | 0 | 2 | 0 |
8 + 2 = 10.
To convert the other way, subtract the largest power of two that fits, then repeat with the remainder. 13 becomes 8 + 4 + 1, or 1101.