Dagesh

A dagesh is a dot inside a letter. There are two kinds:

A dagesh-lene makes the pronunciation of a BGDKFT letter hard; e.g. a ב is pronounced “v”. A בּ is pronounced “b” (note the dagesh). Thus, they will only ever appear in a BDGKFT letter. A dagesh-forte doubles the pronunciation of a letter and will never appear in a guttural. Dagesh-lene are never preceded by a full vowel; dagesh forte are always preceded by a full vowel.

Note #1: letters with a sheva for their vowel will often lose the dagesh; see here.

Note #2: the dagesh in a vav-conversive will never appear in the first letter of the verb root.