ため (or 為（ため） in its kanji form) is a noun in Japanese that can be translated quite closely to ‘sake’ in English. However, it is classified as a 非自立（ひじりつ） (non-independent) word in Japanese, and must always be connected to another word which illustrates the ‘sake’ that ため is highlighting. The 格助詞（かくじょし） (case marking particle) に will often be added after ため, to show that (A) is a goal that something will done to reach.
However, when used with verbs in the past tense, ために more frequently highlights that something happened ‘due to (A)’, rather than ‘for the sake of (A)’. Because of this, a more accurate description of ため in all situations is ‘in light of (A)’. This expresses that (A) is the primary or major event/thing that resulted in (B).
To use ために as ‘in light of’, ‘as a result of’, or ‘because of’, attach it to the end of verb in its past form, or a noun follow by の. It may also be used after い-Adjectives or な-Adjectives in their 連体形（れんたいけい） (attributive form).

• 昨日（きのう）の飲（の）み会（かい）でお酒（さけ）を沢山（たくさん）飲（の）んだために、今日（きょう）は二日酔（ふつかよ）いで身体（からだ）がだるい。
  Because I drank a lot of alcohol at the party last night, I am tired today with a hangover.
• 暑（あつ）いために、職場（しょくば）で何人（なんにん）かが倒（たお）れた。
  Due to it being hot, a few people have passed out at work.
• このアプリは便利（べんり）なために、ユーザーがどんどん増（ふ）えてきた。
  Due to this app being useful, the number of users are steadily growing.
• 大雨（おおあめ）のため、サッカーの試合（しあい）を中止（ちゅうし）します。
  Due to heavy rain, we will be canceling the soccer tournament.

This ‘in light of (A)’ nuance can be used in reference to things that have already happened (as above), or in reference to something that is considered as the purpose of an action (as in our other ために grammar point).

• 空手（からて）の試合（しあい）で勝（か）つために、毎日（まいにち）夜（よる）遅（おそ）くまで練習（れんしゅう）しています。
  In order to win the karate tournament, I practice every day until late at night.
• 昨日（きのう）は夜（よる）遅（おそ）くまで練習（れんしゅう）していたため、今日（きょう）は何（なに）もしたくないです。
  Due to me practicing until late at night last night, I don't want to do anything today.