Preservation of Error- General

Appeals courts generally don't let litigants complain about just anything in the trial below. (Why did I say "generally?" Because there is an important exception I'll talk about next week.) What the appellant complains about must not only be "error." It must be "preserved error."
Judges-- both on trial benches as well as appellate benches-- don't consider it sporting for a litigant to make a complaint about the trial, if the litigant did not tell the trial judge what the litigant thought was a mistake. Normally a litigant shows unhappiness with a particular matter by objecting. Generally, once a judge overrules an objection, that judge has been warned that the litigant might try to complain about that matter on appeal.
It is quite common for some judicial mistake to be just as plain as a pikestaff when the record is reviewed, only nothing can be done-- the lawyer did not recognize the error in the heat of battle.
The opposite of preserving error is "lying behind the log," a near-universal metaphor for a trial participant's holding knowledge of error during the trial, only to try to spring it on the trial judge on appeal.
Principles and pitfalls of preservation of error.: An article from: Florida Bar Journal

Just Say No to Talking, Texting and Tweeting

The blog of Legal Times reports that a committee of the Judicial Conference of the United States has drafted jury instructions to discourage using cell phones or social networking during a trial. Such communications hold the possibility of polluting a jury's ability to decide factual issues at trial under the rulings of the court, producing a lot of unfixable trial error.