Gossip
According to the Thesaurus a "gossip" is "a person habitually engaged in idle talk about others", or it is "idle, often sensational and groundless, talk about others". This activity, spreading gossip, is condemned by scripture several times.
 
Proverbs 16:28 NIV "A perverse man stirs up dissension, and a gossip separates close friends." (See NAB)
Proverbs 26:20 NIV "Without wood a fire goes out; without gossip a quarrel dies down." (See NAB)
2 Corinthians 12:20NIV "For I am afraid that when I come I may not find you as I want you to be... I fear that there may be quarreling, jealousy, outbursts of anger, factions, slander, gossip, arrogance and disorder." (See NAB.)
In Romans he lists them with God-haters: "They are gossips, slanderers, God-haters, insolent, arrogant and boastful; they invent ways of doing evil…" Rom. 1:29-30 NIV. (But see NAB).
On idleness, gossip and busybodies see 1 Tim. 5:13 NIV, NAB; 2 Thessalonians 3:11 NIV, NAB. "The lips of the impious talk of what is not their concern..." Sir. 21:25 NAB.

The danger is that gossip can lead to the sins of rash judgment, detraction, and calumny (slander). Rash judgment occurs when a person accepts something as true without real evidence. If a person says, "Did you hear what happened?" listeners should ask themselves how the speaker knows this. To repeat what someone else has said is not evidence; in court it is hearsay. Did the speaker witness the event and interpret it correctly? It is sinful to believe someone has done wrong when there is little or no real evidence. Even when you know something has occurred, it is open to several interpretations. In politics they call it "spin". The church invites us to put a favorable interpretation on the event whenever possible. CCC sec. 2478. To repeat a true story about another's wrongdoing, to someone who has no need to know it, is the sin of detraction. A person is guilty "who, without objectively valid reason, discloses another's faults and failings to persons who did not know them…" CCC 2477.

"'Backbiting' -- that is, talking evil of persons behind their backs. You would not like your neighbor to backbite you, and you have no right to do to him what you would not wish him to do to you. Besides, everyone hates and fears a backbiter; because as he brings to you a bad story about another, he will in the same manner bring to someone else a bad story about you. It is certainly an honor to be able to say of a person: "He never has a bad word of anyone"; while on the other hand, he must be a despicable creature who never speaks of others except to censure or revile them. Never listen to a backbiter, detractor, or slanderer--it is sinful." The Baltimore Catechism, eight commandment. (cf. Sir. 21:28)

 

Nothing in this teaching prohibits people from sharing valuable or necessary information, good news, acknowledgement of people's talent, praise, etc. The key is to be honest, supportive, and loving; it is to build up the community not tear down.