Sibelius Software is named after Jean Sibelius, a Finnish composer. That makes sense, considering that composition is exactly what their software is designed for. The flagship of the lineup is Sibelius 7.5, a notation program that gives you powerful tools for arranging, printing and playing-back sheet music. Being part of the Avid software family, Sibelius makes a great companion to the Pro Tools digital audio workstation.
Since it's a top choice for notation software, chances are pretty good that you may even be using Sibelius already. If that's the case, and you're looking to expand your toolbox, you'll find upgrades here to make that happen. You could, for instance, upgrade a Sibelius 6 or 7 install to the newer 7.5 update - without having to get a full version of 7.5 to do it. If you're a student, you can also take advantage of the academic versions of Sibelius software and bundles, which are affordable even on a beginner's budget.
For improving the capabilities of your Sibelius software, it's definitely worth looking at a bundle, or upgrading with standalone versions of PhotoScore and AudioScore. These are extensions to the base version of Sibelius that allow you to import music without having to manually write it. PhotoScore can translate an image of sheet music into Sibelius, and AudioScore is capable of "listening" to a music file and writing the sheet music directly. With these add-ons, you can make Sibelius even easier and faster to use.
It doesn't matter if you're a professional audio engineer or recording artist, or simply an aspiring student looking for the best way to get your sheet music down on paper. A good suite of notation software is an essential part of any composer's toolbox, and Sibelius is definitely a solid choice. Write your score by hand in the basic version, or add PhotoScore and AudioScore to generate your sheet music automatically - however you like to use it, Sibelius makes musical notation a breeze.