א (Hebrew aleph) sometimes looks like X when handwritten.

X is the twenty-fourth letter of the Latin alphabet. Its name in English is ex (/ɛks/). In phonetics, x is the IPA and X-SAMPA symbol for the voiceless velar fricative (IPA is used for pronunciation throughout this article). The consonant cluster /ks/ was in Ancient Greece written as Chi 'Χ' (Western Greek) or Xi 'Ξ' (Eastern Greek). In the end, Chi was standardized as Including:

• X - Codes for computing
• X - Meanings for X

Read more here: » X: Encyclopedia - X

In Unicode the capital X is codepoint U+0058 and the lowercase x is U+0078. The ASCII code for capital X is 88 and for lowercase x is 120; or in binary 01011000 and 01111000, correspondingly. The EBCDIC code for capital X is 231 and for lowercase x is 167. The numeric character references in HTML and XML are "X" and "x" for upper and lower case respectively. ...

See also:

X, X - Codes for computing, X - Meanings for X

Read more here: » X: Encyclopedia II - X - Codes for computing