1. Caveat lector is a Latin phrase that means, "Reader, beware (or take heed)". That's good advice regardless of what you are reading.
2. Caveat emptor, quia ignorare non debuit quod jus alienum emit or "Let a purchaser beware, for he ought not to be ignorant of the nature of the property which he is buying from another party."

The well-known shorter version, Caveat Emptor applies to the purchase of land and goods, with certain restrictions, both as to the title and quality of the thing sold. Out of the legal sphere and as a non-legalistic usage, the phrase is used as a warning to a buyer regarding any articles of doubtful quality offered for sale.

This legal terminology means, the purchaser (buyer), not the seller, is responsible for protecting the purchaser (himself or herself) in the transaction. Caveat emptor is the opposite of caveat venditor.

3. Under caveat venditor, the seller is assumed to be more sophisticated than the purchaser and so must bear responsibility for protecting the unwary purchaser.

The purchaser, emptor, is a child who must be protected against his or her own mistakes, while the seller, venditor, is the big, bad wolf lying in waiting for Little Red Riding Hood. So while the two rules struggle for preeminence, attorneys gleefully watch—and litigate."

4. Cave canem means, "Beware the dog". This was used in Roman times and may be seen even now on some gates in Europe. Would anyone be warned sufficiently in the United States if he or she saw this sign on a gate?
5. Cave quid dicis, quando, et cui strongly suggests, "Beware what you say, when, and to whom."

This is certainly good advice for all of us; especially, when writing e-mails or on social websites.

Recent studies have shown that e-mail messages may stay recorded somewhere for years and be available for others to read long after we thought they no longer existed.

A case in point is Bill Gates, whose videotaped deposition for the federal trial in the United States revealed that he couldn't remember sending an e-mail about Microsoft's plans to use Apple Computer to "undermine Sun".

Reading about, "The Tale of the Gates Tapes" in the November 16, 1998, issue of Time, the writer Adam Cohen, wrote, "At a key point in his war against archrival Sun Microsystems, Gates fired off an e-mail about Microsoft's plans to use Apple Computer to 'undermine Sun', but now he can't remember sending the message and has no idea what he could have meant by it."

"Trouble was, it was a difficult line to swallow. Gates as a fuzzy-headed amnesiac? This is the man revered even by the geniuses who roam Microsoft's Redmond, Washington, campus for his awesome 'bandwidth' (geekspeak for intelligence)."

A preposition is always part of a group of words called a prepositional phrase.

A prepositional phrase begins with a preposition and ends with a noun or a pronoun called the object of a preposition.

One or more modifiers may come between the preposition and its object. The prepositional phrases in the following sentences are shown in bold type:

• During our English class, we saw a film about Julius Caesar.
• Because of the snowstorm, traffic was a mess throughout the city."