不如 (bùrú) can be used to make comparisons in a similar way as the 比 structure. In its simplest form 不如 is used to convey that A is 'not as good as' B. Unlike the 比 structure, when used in this way, the adjective or verb can be omitted.

Simple form
Basic Structure

A + 不如 + B
Examples

Wǒ ɡǎnjuékàn diànyǐnɡ bùrú kàn diànshìjù.
我 感觉看 电影 不如 看 电视剧。
I think that watching movies isn't as good as watching TV dramas.

Zhèjiānɡ rén tèbié huì zuò shēnɡyi, lián ɡuǎnɡdōnɡ rén dōubùrútāmen!
浙江 人 特别 会 做 生意，连 广东 人 都不如他们！
People from Zhejiang can really do business, even people from Guangdong aren't as good as they are!

Complex form

When an adjective or verb is added to the structure it can then be used to mean A is not as 'adjective' as B, or A does not 'verb' as well as B:
Basic Structure

A (verb) + 不如 + B + adjective/verb
Examples

Wǒ bùrú yáomínɡ ɡāo.
我 不如 姚明 高。
I am not as tall as Yao Ming.

Chénɡshì de shēnɡhuó huánjìnɡ bùrú xiānɡxiɑ shūfu.
城市 的 生活 环境 不如 乡下 舒服。
The city life environment isn't as comfortable as the countryside.

Tā yònɡ Excelbiǎoɡé bùrú wǒ yònɡ dé hǎo.
他 用 Excel表格 不如 我 用 得 好。
He doesn't use Excel sheets as well as I do.

Zhèɡe yúfǎdiǎn bùrú qiánmiɑnde nàɡè jiěshì dé qīnɡchu.
这个 语法点 不如 前面的 那个 解释 得 清楚。
The explanation of this grammar point isn't as clear as the explanation for the last one.

不如 as an adverb
Basic Structure

不如 + Verb/[verb phrase]

When facing a choice, 不如 can also be used to mean "might as well" to emphasize the choice is the better of two options. When used like this, it is similar in meaning to 不妨.
Examples

jìrán yǐjīnɡ zuòle yíbàn le, nǐ bùrú jiānchí xiàqu.
既然 已经 做了 一半 了，你 不如 坚持 下去。
You've already done half of it, might as well keep going.

Yǔqí kōnɡxiǎnɡ, bùrú mǎshànɡ xínɡdònɡ, zuò chū diánér chénɡjì.
与其 空想，不如 马上 行动，做 出 点儿 成绩。
Rather than fantasizing, might as well take action right away. Achieve something.

As in the last example sentence, 不如 often occurs in the 与其...不如 structure, meaning "rather than X... might as well Y".