1. X band

2. X Bitmap

3. X Pixelmap

4. X protocol

5. X server

6. X Toolkit

7. X Window (X Window System)

8. X.225

9. X.25

10. X.400

11. X.500

12. X.509

13. X+V

14. X11

15. X12ANSI

16. X2

17. X3.92 standard

18. x86

19. x86 emulator

20. Xandros

21. XAPIA (X.4.00 API Association)

22. XBL (eXtensible Binding Language)

23. XDI (XRI Data Interchange)

24. XDOS

25. xD-Picture Card

26. XDR (eXternal Data Representation)

27. XDR (XML-Data Reduced)

28. xDSL

29. XEmacs

30. Xeon

31. Xfce

32. XFDL Extensible Forms Description Language

33. XGA (Extended Graphics Array)

34. XHTML (Extensible Hypertext Markup Language)

35. XHTML+Voice

36. XIP (eXecute In Place)

37. XLib (X LIBrary)

38. XLR connector

39. XML (Extensible Markup Language)

40. XML database

41. XML document

42. XML namespace

43. XML parser

44. XML processor

45. XML Schema

46. XML Schema Language

47. XML tag

48. XML vocabulary

49. XML-Data

50. XML-RPC (eXtensible Markup Language-Remote Procedure Call)

51. Xmodem

52. XMS (eXtended Memory Specification)

53. XNOR (eXclusive NOR)

54. XOR

55. XPath (XML PATH Language)

56. XPCOM (Cross Platform Component Object Model)

57. XPG (X/Open Portability Guide)

58. XPM

59. XPointer (XML POINTER Language)

60. XRI (Extensible Resource Identifier)

61. XSD (XML Schema Definition)

62. XSDL (XML Schema Description Language)

63. XSL (Extensible Style Language)

64. XSL-FO (XSL Formatting Objects)

65. XSLT (Extensible Style Language Transformation)

66. XSS (Cross-Site Scripting)

67. XSSI (eXtended Server-Side Include)

68. XT

69. XT bus architecture

70. XUL (EXtensible User Interface Language)

71. XviD