と has a lot of uses.

As far as I know, と can be uses to point to:

• a member of a complete list (X と Y と Z => noun X AND noun Y AND noun Z)
• a cause of a natural consequence (condition A と natural consequence B => ALWAYS WHEN condition A THEN consequence B)
• a partner also doing the action (person A と action Z => to do action Z TOGETHER WITH person A)
• with certain type of adverbs (the so called "adverbs taking the 'to' particle"), for example しっかり、だんだん etc.
• a quote (X と [person A は] said => "X" said [person A])

The と used here is a quotation particle:

~と言う => to say that ~

~と約束する => to promise that ~

と has a lot of uses.

As far as I know, と can be uses to point to:

• a member of a complete list (X と Y と Z => noun X AND noun Y AND noun Z)
• a cause of a natural consequence (condition A と natural consequence B => ALWAYS WHEN condition A THEN consequence B)
• a partner also doing the action (person A と action Z => to do action Z TOGETHER WITH person A)
• with certain type of adverbs (the so called "adverbs taking the 'to' particle"), for example しっかり、だんだん etc.
• a quote (X と [person A は] said => "X" said [person A])

The と used here is a quotation particle:

～と言う => to say that ～

～と約束する => to promise that ～