When used with the 格助詞（かくじょし） (case-marking particle) に, the う-Verb 沿（そ）う ‘to run alongside’ in its て-form expresses that something is going ‘along with (A)’, ‘in accordance with (A)’, or ‘in line with (A)’. This is primarily in relation to laws, conventions, traditions, needs, and other things which are not usually deviated away from. The nuance with this particular grammar structure is that (A) is the controlling factor, and (B) is being done with that in consideration.
に沿（そ）って may also appear with the verb in its standard form when paired with a second noun, in order to modify that noun.

• 会社（かいしゃ）のルールに沿（そ）って、残業（ざんぎょう）をする方（かた）は必（かなら）ずタイムカードを押（お）してからにしてください。
  In accordance with company rules, please make sure to begin overtime after clocking out.
• クライアント様（さま）の希望（きぼう）に沿（そ）う方向（ほうこう）で進（すす）めたいと思（おも）います。
  We would like to proceed in accordance with the client's wishes.
• ご予算（よさん）内（ない）でお客様（きゃくさま）のご希望（きぼう）に沿（そ）ったお家（うち）を建（た）てれるよう全力（ぜんりょく）を尽（つ）くします！
  We will do our best to build you a home in accordance with your needs and within your budget!

As the base meaning of 沿（そ）う is ‘to follow along’, it will also regularly be seen in relation to going along some specific path or street.

• この点線（てんせん）に沿（そ）って切（き）ってください。
  Please cut along this dotted line.

While this grammar structure is relatively formal, when literally meaning ‘alongside’, it will be used fairly frequently.