to try to do something
-아/어 보다 expresses trying out or experiencing an action, and corresponds to 'try' in English.
When the verb stem ends in ㅏ or ㅗ, -아 보다 is used.
Otherwise -어 보다 is used.
For verbs that end in 하다, the form changes to -해 보다.
In general, when used with the present tense, it expresses trying something, and when used with the past tense, it expresses having the experience of doing something.
When -아/어 보다 is used to express the experiencing of something, it is not used together with the verb 보다.
Expresses the meaning of trying something out or experiencing an action.
Both versions [아/어]보다 and 아/어 보다 (with space) exist and can be used interchangeably. source