Images are placed in a <img>
Empty element meaning there is no closing tag
<img src="images/team_hands" alt="a group of people touching hands in a star formation" title="teamwork is awesome">
src - Tells browser where to find the image (may relative or absolute path)
alt - Provides description of image for people who cannot see the image (accessibility)
title - Used to provide additional information about the image. Most browsers will display this information in a tooltip.
.png - Supports transparency and semi-transparency, great for logos, icons, and repeating background tiles. Almost always preferable to a gif.
.gif - Can have basic transparency, typically a png is used instead
.jpeg - No transparency, can be stored at different compression levels with varying amounts of “lossy-ness”, typically the best format for photos