panel 1: let’s talk about how to write binary data

one way: binary

01111111 11111111 11111111
it’s easy to see the bits…

1010110110101001010
but it’s hard to read a lot of them

another way: base 10
83888607
but I have NO IDEA how many bits that is

panel 2: now the best way to write binary data: base 16!

It’s short AND maps well to bits!
7fffff
Every hexadecimal digit represents 4 bits. So 1 byte (8 bits) is always 2 hexadecimal digits.

panel 3: there are 16 hex digits: 0 → f

| hex | decimal | binary |
| 0   | 0       | 0000   |
| 1   | 1       | 0001   |
| 2   | 2       | 0010   |
| 3   | 3       | 0011   |
| 4   | 4       | 0100   |
| 5   | 5       | 0101   |
| 6   | 6       | 0110   |
| 7   | 7       | 0111   |
| 8   | 8       | 1000   |
| 9   | 9       | 1001   |
| a   | 10      | 1010   |
| b   | 11      | 1011   |
| c   | 12      | 1100   |
| d   | 13      | 1101   |
| e   | 14      | 1110   |
| f   | 15      | 1111   |

panel 4: 0x means it’s hex

In many languages, the 0x prefix lets you write numbers in hexadecimal.
For example, in C:
0x20 == 32 (base 16)
0b10100 20 (base 2)
061 == 49 (base 8)
be careful: the 0 prefix meaning “base 8” can really trip you up!

panel 5: things hexadecimal is used for

color codes! (e.g. #FF00FF)
memory addresses!
hashes! (like git commit IDs)
displaying binary data! (like with hexdump)