The graphic identity of an Olympics is very important business. Each host of the games puts a lot of money and consideration into designing logos, pictograms, and general branding, such as posters, clothing, gifts, and signage. It's vital that these graphics are memorable, relevant, and aesthetically pleasing.
Someone once said that "no design works unless it embodies ideas that are held common by the people for whom the object is intended." The official logo of each Olympics is intended not only for citizens of the host nation, but for the entire world. By that standard, creating the identity of an Olympics is perhaps the toughest job for a designer.
On the Logo pages for each Olympic Games that you can access below, you will not only find images and descriptions of each games' official logo, but also for that of their bid logo, their pictograms, and any other graphic branding and identity.