ASCII stands for American Standard Code for Information Interchange. Currently, there are a heck of a lot of characters codes in ASCII. However, most of them are not commonly used. The most seen ASCII characters occur in the basic ASCII (from 1 to 127 inclusive).
Just some notes: Characters 1 thru 31 are control characters, meaning they may represent the carriage return, escape key, and backspace key just to name a few. Characters 48 thru 57 are the numbers 0 thru 9 respectively. Characters 65 thru 90 are the uppercase letters while characters 97 thru 122 are the lowercase letters.
Below is an ASCII chart of most of those 127 characters(character 32 thru 126 as they are the most commonly seen). This chart also may help you for the challenges that use character arithmetic and ASCII codes.
| Code | Char | Code | Char | Code | Char | Code | Char | Code | Char |
| 32 | | 51 | 3 | 70 | F | 89 | Y | 108 | l |
| 33 | ! | 52 | 4 | 71 | G | 90 | Z | 109 | m |
| 34 | " | 53 | 5 | 72 | H | 91 | [ | 110 | n |
| 35 | # | 54 | 6 | 73 | I | 92 | \ | 111 | o |
| 36 | $ | 55 | 7 | 74 | J | 93 | ] | 112 | p |
| 37 | % | 56 | 8 | 75 | K | 94 | ^ | 113 | q |
| 38 | & | 57 | 9 | 76 | L | 95 | _ | 114 | r |
| 39 | ' | 58 | : | 77 | M | 96 | ` | 115 | s |
| 40 | ( | 59 | ; | 78 | N | 97 | a | 116 | t |
| 41 | ) | 60 | < | 79 | O | 98 | b | 117 | u |
| 42 | * | 61 | = | 80 | P | 99 | c | 118 | v |
| 43 | + | 62 | > | 81 | Q | 100 | d | 119 | w |
| 44 | , | 63 | ? | 82 | R | 101 | e | 120 | x |
| 45 | - | 64 | @ | 83 | S | 102 | f | 121 | y |
| 46 | . | 65 | A | 84 | T | 103 | g | 122 | z |
| 47 | / | 66 | B | 85 | U | 104 | h | 123 | { |
| 48 | 0 | 67 | C | 86 | V | 105 | i | 124 | | |
| 49 | 1 | 68 | D | 87 | W | 106 | j | 125 | } |
| 50 | 2 | 69 | E | 88 | X | 107 | k | 126 | ~ |