In a similar way to みたい, ようだ is used when making observations about something in Japanese. This 助動詞（じょどうし） (auxiliary verb) is used to express three primary things.
たとえ - Using (A) as an example to highlight the way that (B) looks/is acting.
推定（すいてい） - Using (A) as a reason for an assumption made about (B).
例示（れいじ） - Presenting (A) as an example of what (B) is.
ようだ is usually based on direct information/experience, and shows that the speaker has high confidence in what they are saying. It may also frequently appear in its kanji form, 様（よう）だ.
ようだ can be used with any verb, い-Adjective, な-Adjective, or noun. However, it requires な before it when used with な-Adjectives, or の when used with nouns.

• ここに大（おお）きなビルが出来（でき）るようだ。
  It seems like a big building will be made here.
• あそこのプールは深（ふか）い様（よう）だ。
  It seems like the pool over there is deep.
• 彼（かれ）は明日（あした）のテストに自信（じしん）があると皆（みんな）に言（い）っているが、本当（ほんとう）は不安（ふあん）なようだ。
  He is telling everyone that he is confident about the test tomorrow, but it seems like he is actually worried.
• ヨーダは宇宙人（うちゅうじん）のようだ。
  Yoda appears to be an alien.

Although ようだ and そうだ are often used in similar situations, そうだ shows that the speaker has a lot less confidence in their statement than ようだ. Because of this, ようだ is a much better choice when stating things that are obvious/observable by anyone.