Facebook began public trading today at $38 a share and a valuation of $104 billion. These are the top 25 apps on the social network the day of its initial public offering, as tracked by our AppData traffic monitoring service.

We’ll start with daily active users, which is a measure of the most engaged portion of an app’s audience. Note that of these apps, nine are Facebook canvas games. The others are mobile apps, web integrations, desktop apps or a combination. For example, Words With Friends is a canvas and mobile game, Spotify is a desktop and mobile app, and Socialcam has a mobile app, website and canvas presence. The top app, Microsoft, is a web utility that connects Windows Live to a user’s Facebook account.

1.	Microsoft	12,100,000
2.	Draw Something	9,100,000
3.	Texas HoldEm Poker	7,100,000
4.	Words With Friends	7,100,000
5.	Bubble Witch Saga	6,400,000
6.	HTC Sense	5,900,000
7.	CityVille	5,600,000
8.	CastleVille	5,200,000
9.	Yahoo!	5,200,000
10.	Spotify	5,000,000
11.	Astrology	4,900,000
12.	Hidden Chronicles	4,700,000
13.	Yahoo! Social Bar	4,700,000
14.	schoolFeed	4,600,000
15.	FarmVille	4,500,000
16.	Diamond Dash	4,300,000
17.	Socialcam	4,200,000
18.	Zynga Slingo	4,200,000
19.	Bing	4,000,000
20.	Samsung Mobile	3,700,000
21.	DROID	3,500,000
22.	Tetris Battle	3,500,000
23.	Photo Love	3,300,000
24.	Bejeweled Blitz	3,200,000
25.	Daily Horoscope	3,100,000

Next, we present the top 25 Facebook applications in size by monthly active users. This is a measure of an app’s overall reach. By launching Open Graph integrations, many of these apps have rapidly climbed our rankings in the past months, and drawn excessive media attention whenever traffic plateaued or decreased. Of these apps, nine are Facebook canvas games — and they’re not all the same games that appeared in the top 25 DAU list above.

1.	Socialcam	51,500,000
2.	Yahoo! Social Bar	39,500,000
3.	CityVille	36,900,000
4.	Viddy	36,900,000
5.	Texas HoldEm Poker	35,000,000
6.	Draw Something	30,600,000
7.	Static HTML: iframe tabs	29,700,000
8.	MyCalendar – Birthdays	29,000,000
9.	Bing	25,700,000
10.	Microsoft	22,800,000
11.	FarmVille	22,400,000
12.	Scribd	22,200,000
13.	CastleVille	22,100,000
14.	Hidden Chronicles	21,800,000
15.	Angry Birds	21,400,000
16.	Bubble Witch Saga	21,200,000
17.	Spotify	19,700,000
18.	TripAdvisor™	19,300,000
19.	Diamond Dash	18,900,000
20.	Samsung Mobile	18,700,000
21.	Static Iframe Tab	18,500,000
22.	Metacafe	17,900,000
23.	Words With Friends	17,600,000
24.	Instagram	16,700,000
25.	Tetris Battle	15,800,000

Be sure to catch up on Inside Facebook’s IPO coverage and stick with us to see how the app ecosystem evolves with the social network’s new status as a public company.