Abbreviations are handy little devices for communicating quickly and for conserving precious space online. But some abbreviations are so often misused that they’re not worth the time and space savings. That’s the case with the abbreviations i.e. and e.g., as illustrated by Yahoo! Style:
Even if the writer had included the period after the E and a comma after the entire abbreviation, it would still be wrong. The abbreviation stands for the Latin id est, which means that is. The writer meant e.g., the abbreviation used before an example.
These abbreviations are not only used incorrectly by most writers, but they’re also misunderstood by 90% of all readers. So why risk using the wrong abbreviation and confounding your readers? There are simple words (e.g., that is or for example) that you can use with confidence.