とされている is an expression that is commonly translated as ‘to be considered as (A)’, or ‘to be regarded as (A)’. Conceptually, it is similar to
にする, which means ‘to decide on (A)’. However, due to
する being in the
passive form in this construction, it is closer to ‘to be decided on’, and expresses the general opinions/thoughts of large groups of people.
The
と in this expression is a 格助詞（かくじょし） (case-marking particle) and expresses the 結果（けっか） ‘result’ nuance of this particle.
-
今（いま）の時（じ）代（だい）にはインターネットが必要（ひつよう）だとされている。
In current times, the internet is widely considered to be necessary.
-
これは二コラテスラが発明（はつめい）したものだとされている。
This is considered to be something invented by Nikola Tesla.
The main difference between
と as a 格助詞（かくじょし） (case-marking particle) and
と as a 接続助詞（せつぞくじょし） (conjunction particle) is that the case-marking particle will always link a single word/phrase to one specific word/result. The conjunction particle on the other hand, will often be followed by a 読点（とうてん） (Japanese comma), as it is separating two distinct thoughts within the sentence, rather than just a simple ‘result’.
-
水（みず）は氷（こおり）となる。
Water becomes ice. (As a result of transformation, water will be ice)
-
温度（おんど）が0度（ど）になると、水（みず）は氷（こおり）となる。
If the temperature is 0 degrees, it results in water becoming ice.