Daily Halacha

1. Chazal viewed the recitation of אמן very highly and compared its recitation to a signature that attests to the validity of a document. In fact, Chazal tell us that responding אמן is of greater significance than reciting the Beracha. The failure to recite אמן is considered a gross transgression, while responding אמן with great concentration opens the gates of Gan Eden.
2. The letters of אמן are the root letters of the word אמונה, belief or trust. By responding אמן one declares: "I believe in the blessing that I have just heard and I affirm its truth." Additionally, when responding אמן one should have in mind the beginning of the Beracha, ברוך אתה ה', that Hahshem's name is Blessed. Thus, for example, when responding אמן after מגן אברהם, one should have in mind, "The Name of Hashem should be blessed, and it is true that He shielded our forefather Avrohom, and I believe it".
3. One should answer אמן to any blessing one hears whether he wishes to fulfill an obligation, or even if one overhears a Beracha. One should respond אמן after each line in Bircas Hamazon that begins הרחמן. Moreover, the obligation to respond אמן even applies to a ברכה that does not contain Hashem's Name, such as answering to a Mi Sheberach.
4. The proper intention of the word אמן changes with the Beracha. When answering אמן to ברכות המצוה or ברכות הנהנין-Mitzvoh Berachos or Berachos on enjoying things, one's intention should be to affirm the truth of the Beracha and his belief in it. When answering to ברכות השבח, one should have in mind that he is affirming the truth of that praise. When responding אמן to תפילות one's אמן should be an entreaty to Hashem to fulfill that prayer. At times, ברכות can have multiple purposes and as such one should have multiple כוונות
5. When reciting Kiddush on Friday night, we say the words ויהי ערב ויהי בקר quietly before saying יום הששי. In truth, ויהי ערב is actually the second part of the Passuk which precedes יום הששי. We don’t say those words out loud because the first letters of יום הששי ויכלו השמים form the name of Hashem-הויה. While we generally avoid reciting Pesukim in ways which differ from their presentation in the Torah, "כל פסוקא דלא פסקיה משה אנן לא פסקינן", nonetheless we only say the second part, and don't say the first part of the Passuk quietly because Chazal Darshen the words "טוב מאד" as referring to death.