What is the function of the following components in media? :

When agar is added to media, it gels and creates a solid surface for the bacteria to grow on; without agar, the media would just be a liquid broth and no distinct colonies would form. Agar is a solidifying agent, similar to gelatin.

"Peptone" is essentially the result of the enzymatic digestion of proteins, most commonly animal proteins; peptone provides the nitrogen and/or amino acid sources that bacteria require to synthesize proteins on their own.

Most organisms use glucose as a common source of carbon (and energy). In media, bacteria use glucose as a carbon source to synthesize important biomolecules like amino acids, nucleic acids, and carbohydrates, and to provide the energy needed for all other necessary functions.

A pH indicator called neutral red is used to determine if the medium is too acidic (pH less than 6.8). If this happens, neutral red will turn the medium a deep red color, suggesting that the bacteria may be starving for oxygen or nutrients.

Thioglycolate is a component added to media when we want to grow only those bacteria that thrive when oxygen is absent. It effectively removes oxygen from the growth substrate, making the media selective for anaerobic (bacteria that do not grow in the presence of oxygen) and facultative anaerobic (prefer to grow in the absence of oxygen, but can grow with oxygen present, albeit less robustly) bacteria.

It looks like the question is incomplete, as it doesn't specify which components in media you're referring to. Could you please provide more context or clarify your question?