TTF files are files that used a font developed by Apple in the 1980s to compete with Adobe's Type 1 Fonts. Since then, TTF has become one of the most common fonts for both Mac OS and Windows. However, other fonts have also been used–OpenType and ClearType. Regardless, many computers are able to open TTF files so long as they have the proper font installed.
The first step to open a TTF file is to move it to your hard drive or insert a CD that has the file on it. What you are looking to do is install the font so that you can access the file.
Click your start button and then go to your control panel. Allow the control panel to load so that all of the tabs are now available. Locate the fonts tab. Depending on how big your screen is and if you have the folder open all the way will determine which row the Fonts tab is. Double click on it and allow the folder to open.
Open the folder with the TTF file and locate the font. Take that font and drag it into the Font folder. When you drop it in there, the font will be installed to the computer. Drop it in and then attempt to open the TTF file that you want to view. It should open because the font is now available to you. Because the font is available, you'll be able to access TTF in the future on other programs.
While there are other formats used today, TTF is still one of the most popular formats. Because of that, it is important to have TTF font installed on your computer. The above process is the way to install new fonts regardless of the type. Simply locate the font file and drag it into the Fonts tab found on your control panel.