Official Warner Bros. Synopsis:
In the wealthy, seaside community of Neptune, California, the rich and powerful make the rules. Unfortunately for them, there's Veronica Mars, a smart, fearless 17-year-old apprentice private investigator dedicated to solving the town's toughest mysteries. Veronica used to be one of the popular girls, but it all came crumbling down around her after her best friend, Lilly, was murdered, and her then-sheriff father, Keith, was removed from office for naming Lilly's rich father as the lead suspect. During the day, Veronica must negotiate high school like any average teenage girl. But at night, she helps with her father's struggling, new private investigator business--and what she finds may tear the town of Neptune apart at the seams.

Logan and Veronica's on-again/off-again tumultuous relationship was one of the most debated subjects on this show (hey, it even came with a catch nickname). Whether you loved them or hated them, you can't deny that their ups and downs were fascinating to watch.
Some of their best moments:
When Logan gave his speech about their "epic" love
Their first kiss at the end of season one

Season 1 Mystery
Duncan, Lilly's brother, dumped Veronica with no explanation right before Lilly's death. Then Veronica sided with her dad in the Jake Kane investigation, causing all her friends to shun her. Then her mom ran off. Then she woke up after a party realizing she'd been drugged and raped. All that was laid out in the pilot. Eventually, Veronica found out that she and Duncan had sex at the party, both under the influence of GHB. He lived with the guilt of having slept with his alleged sister for months, so he was pretty stoked to learn he and Veronica aren't related. The other shocker was that Lilly was sleeping with Aaron Echolls, and he killed her.

Season 2 Mystery
Well, there were two big mysteries laid out in the season premiere. One is that Felix, Weevil's second-in-command in the PCH gang, was knifed to death. Logan was accused of the crime, but the culprit was actually fellow gang member Thumper, who was in league with a local family of Irish ruffians, the Fitzpatricks. Weevil caused Thumper to pay the ultimate price, though. The other is that a busful of kids went over a cliff. Despite (or perhaps because of ) an overly intricate web of minor players and red herrings, Veronica ho-hummed her way through the entire season before discovering that the adorable Beaver Casablancas was, in fact, a psychotic serial killer. Many people enjoyed this resolution, and we're very happy for them.

Veronica's Mom
Veronica's boozebag mom, Lianne, left after Keith lost his job as Neptune sheriff. She wasted a bunch of Veronica's money on rehab that she didn't go through with, and then stole fifty grand from Keith before taking off again, ideally never to return. She's a tulip. On the plus side, she wasn't around to get in the way of Keith's romance with Alicia, Wallace's mom, but that relationship unfortunately imploded without any help from her.

Enough HoYah! to Rival Smallville
Oh, that's quite an exaggeration. We mean, there was the time Logan talked about his cojones with Weevil. And the time Logan got on his knees in front of Weevil while talking about the prom. And the time Logan and three other guys stripped down to their boxers while Weevil checked out their packages. But other than that, there hasn't been much at all.

Veronica's Two Dogs
Her pit bull, Backup, was originally white, but there were some performance problems. Actors, you know. Backup 2.0, the recast, is sort of orangey or something. Also, adorable. For a pit bull.

The 09ers
The rich kids in Neptune are nicknamed "09ers" after the 90909 zip code wherein they apparently all live. Sort of like 90210, but you won't find Ohndrea Zuckerman there.

Lily's Age
Lily was a year older than Duncan, Logan, and Veronica. This has never been stated expressly on the show, but the show's creator told TWoP how it is. He should know, right?

Season 1
01 Pilot
02 Credit Where Credit's Due
03 Meet John Smith
04 The Wrath of Con
05 You Think You Know Somebody
06 Return of the Kane
07 The Girl Next Door
08 Like a Virgin
09 Drinking the Kool-Aid
10 An Echolls Family Christmas
11 Silence of the Lamb
12 Clash of the Tritons
13 Lord of the Bling
14 Mars vs. Mars
15 Ruskie Business
16 Betty and Veronica
17 Kane's and Abel's
18 Weapons of Class Destruction
19 Hot Dog
20 M.A.D.
21 A Trip to the Dentist
22 Leave it to Beaver

Season 2
23 Normal is the Watchword
24 Driver Ed
25 Cheatty Cheatty Bang Bang
26 Green-eyed Monster
27 Blast from the Past
28 Rat Saw God
29 Nobody Puts Baby in a Corner
30 Ahoy Mateys
31 My Mother, the Fiend
32 One Angry Veronica
33 Donut Run
34 Rashard and Wallace Go to White Castle
35 Ain't No Magic Mountain High Enough
36 Versatile Toppings
37 The Quick and the Wed
38 The Rapes of Graff
39 Plan B
40 I Am God
41 Nevermind the Buttocks
42 Look Who's Stalking
43 Happy Go Lucky
44 Not Pictured

Season 3
45 Welcome Wagon
46 My Big Fat Greek Rush Week
47 Wichita Linebacker
48 Charlie Don't Surf
49 President Evil
50 Hi, Infidelity
51 Of Vice and Men
52 Lord of the Pi's
53 Spit and Eggs
54 Show Me the Monkey
55 Poughkeepsie, Tramps and Thieves
56 There's Got to be a Morning After Pill
57 Postgame Mortem
58 Mars, Bars
59 Papa's Cabin
60 Un-American Graffiti
61 Debasement Tapes
62 I Know What You'll Do Next Summer
63 Weevils Wobble But They Don't Go Down
64 The Bitch is Back

   * Veronica Mars (Kristen Bell)

   * Logan Echolls (Jason Dohring)

   * Wallace Fennel (Percy Daggs III)

   * Eli "Weevil" Navarro (Francis Capra)

   * Keith Mars (Enrico Colantoni) 

   * Duncan Kane (Teddy Dunn) 

   * Mallory Dent (Sydney Tamiia Poitier)

   * Dick Casablancas Jr. (Ryan Hansen)

   * Cassidy "Beaver" Casablancas (Kyle Gallner)

   * Jackie Cook (Tessa Thompson)

   * Cindy "Mac" MacKenzie (Tina Majorino)

   * Sheriff Don Lamb (Michael Muhney)

   * Parker Lee (Julie Gonzalo)

   * Stosh "Piz" Piznarski (Chris Lowell)