How can I disable the random/auto keeping of apps in the Dock?

Sometimes the Dock will keep an icon app in the Dock, even though I haven't set it as such, even though I've previously de-kept it in Dock after the first time it kept it 'for me'.

Is there a way to turn this off it's a bit annoying?

Solution 1:

Usually apps don't place themselves in the dock without your consent or knowledge. There are a couple ways to put them there though. Perhaps you may not realize it, but it may be one of these reasons:

1. The App Store will place an app in the Dock upon installation. Note: Lion will not do this though; it simply places it in Launchpad.
2. The App Store will place an app in the Dock upon updating an app. Note: Updating an non-docked app individually via the updates tab is when it gets re-placed in the dock. However using the 'Update All' button at the top of the page will not do any such thing. Again, this is changed in Lion.
3. If you run an app that is not kept in the dock and drag it to another position anywhere on the dock, it will stay in the dock
4. Drag an app into the dock from Finder
5. Right click an app in the dock an under options select 'Keep in Dock'

Solution 2:

go to "system preferences", then choose "Dock" and uncheck the "show recent applications in dock" radio button.