The trade sessions indicator. The indicator colors eight trade sessions by rectangles. The periods of sessions defined by indicator input parameters:

//+-----------------------------------+
//|  INDICATOR INPUT PARAMETERS       |
//+-----------------------------------+
input int    NumberOfDays=50;
input string S1Begin   ="00:55";
input string S1End     ="03:55";
input color  S1Color   =clrDarkSlateGray;
input string S2Begin   ="03:55";
input string S2End     ="06:55";
input color  S2Color   =clrDarkSlateGray;
input string S3Begin   ="06:55";
input string S3End     ="09:55";
input color  S3Color   =clrDarkSlateGray;
input string S4Begin   ="09:55";
input string S4End     ="12:55";
input color  S4Color   =clrDarkSlateGray;
input string S5Begin   ="12:55";
input string S5End     ="15:55";
input color  S5Color   =clrDarkSlateGray;
input string S6Begin   ="15:55";
input string S6End     ="18:55";
input color  S6Color   =clrDarkSlateGray;
input string S7Begin   ="18:55";
input string S7End     ="21:55";
input color  S7Color   =clrDarkSlateGray;
input string S8Begin   ="21:55";
input string S8End     ="23:55";
input color  S8Color   =clrDarkSlateGray;

This indicator was first implemented in MQL4 and published in Code Base at mql4.com on 26.09.2007. 

Fig.1 The i-Sessions indicator