A cataract is a cloudy area in the normally clear lens of the eye. Most cataracts are due to age-related changes in the lens. For more information on cataracts, please visit the American Optometric Association's webpage on Cataracts.
The website for Omni Eye Services is a great resource for information on cataracts and cataract surgery options. This link on their website also explains the advantages of Laser Cataract Surgery vs Traditional Cataract Surgery.
Johnson & Johnson Vision and TECNIS offer a vision simulator here, with details regarding intra-ocular lens (IOLs or "implants") options.
Alcon also offers valuable information about cataracts and IOL options here.