is "the former" and
"the latter": they point back to two things just named, the first and the second, so you don't have to repeat them. They are nouns, written and formal, and usually come as a pair in a sentence that contrasts the two.
、、。
Of dogs and cats, the former are loyal and the latter independent.
。、。
Tanaka and Yamada applied. The former has plenty of experience, and the latter is young and keen.
、、。
Comparing Tokyo and Osaka, the former has a larger population and the latter a richer food culture.
The two things have to be named first, in order; 前者 is always the one mentioned first. They only work for two – with three or more, name each one again.
One of the two
You can use just one of them when only one matters. Then they take whatever particle the sentence needs, not only は.
、。
There are two proposals, but the latter is more realistic.
、。
Two opinions came up, and I agree with the former.
、。
I tried two methods, and the latter worked better.
In conversation, people repeat the nouns instead: rather than 前者のほうが安かった.
Lingaku