Widget Logic Visual Version lets you control on which pages widgets appear using WP's conditional tags without having to know how conditional tag
Once the plugin is installed, the bottom of every widget has a new "edit visibility" button like the one in this image. Just click that button to restrict where the widget will display on your website (otherwise it will show on all pages)
Once you click that buton you get a lightbox popup window to choose "add new limitation (visual)" or "using conditional tag code (advanced). Click one or the other to get started.
Once you click "add new" you get a dropdown to choose where to show the widget (homepage, posts, pages, tags, categories, 404 page, author pages). Choose the places you want to show the widget or click "except" to not show the widget on those pages. This example shows adding a limitation for all category pages. Choose all or any you'd like to display on.
In this example we see how if you uncheck "all categories" a multi-select box appears where you can select one or more individual category pages (if you don't want them all). The same thing happens if you uncheck "all" for posts, pages, authors, attachments, tags, etc.
An example of adding a limitation to make a widget show on every page of the website except the homepage.
This is an example of adding conditional tag code. You must add the code and check the "activate the code" and click "update" for it to work. This is in case you want to try a conditional tag, de-activate it (to try a visual version) and then come back later to activate it again (the code you last used is saved in the box).
This is an error illustrating what will happen if you try to add both conditional tag code and a visual limitation (you can't have both, it's one or the other)