By default, most SharePoint 2010 solutions created in Visual Studio 2010 will be globally deployed to SharePoint farms. It doesn't matter if you deploy directly from Visual Studio or use any of the other methods like deploying using PowerShell. In SharePoint 2010 Central Administration under System Settings -> Farm Management -> Manage farm solutions you will find your solution to carry the Deployed To Globally deployed status:
This has several disadvantages:
First, deploying solutions globally will cause
all webapplications on the farm (including central administration) to be targeted and thus receive an IIS Pool recycle. Even though your solution was specifically for one webapplication, all others will also be braught down for a minute.
Second, Visual Studio 2010 by default enabled all features in solutions after deploying them. This will enable the features in the solution to be enabled on all webapplications on the farm including central administration. Imagine having a solution which modifies the web.config, this will therefore happen to all webapps which is not a good thing.
Third, it doesn't allow you to easily identify what solutions belong to what webapplications.
To avoid this from happening, there is an easy workaround: