Defend base missions in Starcraft 2

I just started playing the campaign. How many defend base missions are there?

Eh theres a good amount. They're extremely fun too.

On the first base defense map, if you have the balls to rush a bunch of Marine and Medic to the top North point of the map, you'll discover a really really cool easter egg. Some sort of character from another world launch to space in a portable toilet. It's weird as hell. epichotcheese

oh ya? i know a cooler easter egg. in the devil playground mission (the level wehre the lava rises every few minutes), if you go south east (would require killing/destroying a few zerg bases) on the lava, you can seemarine size diablo (from diablo franchise) just doing some cool animated movements. best easter egg in the game possibly. i recommend checking it out

There are a few. Try to complete "The Dig" mission as soon as possible, it gives you siege tanks, which are awesome.

There are like 4 or 5 at least, but each one is unique and all are very fun.

[spoiler] Stuff like using a giant laser drill or zombie survival [/spoiler]

This is the easter egg I was talking about:

http://www.youtube.com/watch?v=mZPf0mfq3zI

Character from World of Warcraft launching into space in a toilet LOL