LOLCODE

HAI 1.2
CAN HAS STDIO?
VISIBLE "HAI WORLD!"
KTHXBYE

Code	Comment
HAI [VERSION]	In all LOLCODE programs, HAI ("Hi!") introduces the program and specifies the version (although this isn't actually used yet).
CAN HAS [LIBRARY]?	In many programming languages, one of the first statements will be a library inclusion for common functions such as input and output. Typically this is included by a call such as #include <stdio.h> (stdio standing for standard input/output library). This command is a tongue-in-cheek corruption of that, asking if a library is obtainable, obtaining it if possible, and raising an exception if not.[6] It is there primarily for verisimilitude—in fact, it is ignored in current implementations of LOLCODE.
VISIBLE [MESSAGE]	Prints a message to the screen.
KTHXBYE	Just as HAI introduces the program, KTHXBYE (which is "K," "THX," and "Bye" all strung together, meaning "OK, thanks, bye") terminates it.
BTW [MESSAGE]	To write a single line comment in LOLCODE, you use the BTW keyword. Comments are ignored by the compiler and are written for better understanding of the program.
OBTW [MESSAGE]TLDR	Similar to the BTW keyword, the OBTW keyword marks a multiline comment, a comment that spans multiple lines. In LOLCODE, the OBTW keyword signifies the start of a multiline comment while the TLDR keyword ends it.

HAI 1.2
CAN HAS STDIO?
PLZ OPEN FILE "LOLCATS.TXT"?
    AWSUM THX
        VISIBLE FILE
    O NOES
        INVISIBLE "ERROR!"
KTHXBYE

In this example,[5] commands to open a file (PLZ OPEN FILE "NAME"?—"Please try to open a file?"), and error handling (AWSUM THX—"Awesome, thanks!", and O NOES—"Oh no!") are introduced.

Other commands include I HAS A variable for declaring variables, variable R value ("variable [is/are/being] value") for assigning them, sending error messages to the front end via INVISIBLE instead of VISIBLE, and BTW ("by the way") to denote a comment, making the parser ignore the rest of the line.

Loops are created with IM IN YR ''label'' (inspired by the "Im in ur noun, verbing yr related noun" LOLcat meme), and ended with IM OUTTA YR ''label''. Loops can be broken with the keyword ENUF ("enough"), or in older versions, GTFO.[7] Loops can also be ended with the conditional IZ command, as demonstrated in the next example.

HAI 1.0
CAN HAS STDIO?
I HAS A VAR
IM IN YR LOOP
    UP VAR!!1
    VISIBLE VAR
    IZ VAR BIGGER THAN 10? KTHX
IM OUTTA YR LOOP
KTHXBYE

[5]

This simple program displays the numbers 1–11 and terminates (as of specification 1.0). The same program as of specification 1.2 is (assuming VAR starts at 0):

HAI 1.2
CAN HAS STDIO?
IM IN YR LOOP UPPIN YR VAR TIL BOTH SAEM VAR AN 10
    VISIBLE SUM OF VAR AN 1
IM OUTTA YR LOOP
KTHXBYE

HAI 1.0
CAN HAS STDIO?
VISIBLE "U SEE THIS"

BTW VISIBLE "U SEE NOTHING"

OBTW
VISIBLE "U SEE NOTHIN"
VISIBLE "U STIL SEE NOTHIN"
TLDR

VISIBLE "U SEE THIS"
KTHXBYE

The above example will return the following:

U SEE THIS
U SEE THIS

This is because line 3 outputs U SEE THIS but line 5 is ignored due to the fact that it is commented out by the BTW keyword. Lines 8 and 9 aren't run because they are in a multiline comment that starts in line 7, and ends on line 10. Line 12 outputs U SEE THIS and line 13 terminates the program.