Tags are strings that are attached to items on a complex widget ([text] or [canvas]), or to groups of bindings (see [bindtags]). An item can have several tags. After assigning them, you can perform actions on a tag, which will be done with all the tagged items. ([RS])

'''Usage examples:'''
 canvas .c
 # On canvases, tags are known only if at least one item has it
 foreach i {1 2 3 4 5} {
     .c create rect [expr $i*10] 0 [expr $i*10+8] 8 -tag box
 } ;# create multiple canvas objects
 .c itemconfig box -fill red ;# to change their color
 .c lower box ;# to hide them behind a background area

 text .t
 # On text widgets, tags persist even without instances 
 .t tag config bold   -font {helvetica 12 bold}
 .t tag config hilite -bg orange
 .t insert end Hello
 .t insert end world bold ;# tags come as 4(6,8..)th element
 .t insert end "out there" {bold hilite}
 .t tag config bold -font {times 11 bold}  ;# change and reformat all
 

[[tutorials]]

[[examples in books, including Effective, JO's, ...]]