# What is the default font type (OT1, T1, T3, etc.) used in AMS document classes (amsart, etc.)

Today I read several articles that suggested using Type 1 fonts in LaTeX (and they claim that Type 3 fonts are the default in LaTeX, which lead to terribly rendered PDF documents). Personally I didn't quite get the technical points about font types, or the technical points about compiling to dvi, ps, and pdf. Anyway, I never got terribly rendered PDF documents either. For me, I always use ams document classes, and compile to PDF using the default `LaTeX` command in AUCTeX with `TeX-pdf-mode` turned on—kind of like pressing a GUI button, with all technical details hidden from me. I tried to follow the suggestions to switch to Type 1 font (of Computer Modern):

``````\usepackage[T1]{fontenc}
\usepackage{ae,aecompl}
``````

However, I didn't notice any difference in the outcome. Therefore, I'm curious about if Type 1 font is the default font type in ams document classes. If it is not, on the other hand, should I switch to Type 1 font (with the above code) for better quality?

As I've pointed out, I don't understand the technical points about fonts, so sorry if this question is non-sensical. (If it is, please point it out to me!)

By the way, my TeX distribution is TeXLive-2013 provided by MacTeX, in case this is relevant.

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The packages `ae` and `aecompl` are considered obsolete. If you write in English, you shouldn't need `fontenc` either. –  egreg Jan 9 at 20:18
T1 is not a font type but an encoding. It has nothing to do with type1 fonts. Keep `\usepackage[T1]{fontenc}` but remove ae and aecompl. That's not longer needed if you have the cm-super fonts installaed (which should be the default in texlive). –  Ulrike Fischer Jan 9 at 20:18
@egreg: T1 is useful for english too. E.g. try `< abc > \ttfamily \{abc\}` with and without T1-encoding. –  Ulrike Fischer Jan 9 at 20:28
@UlrikeFischer Sorry I mixed up different concepts. Should I edit the question so it makes more sense? (Or would you please edit it for me since I'm still somewhat confused? Thanks.) –  KevinSayHi Jan 9 at 20:34

the ams document classes specify only computer modern fonts, all available as type 1. however, these fonts are based on `OT1` encoding, which is suboptimal for languages with accented letters.
using the "latin modern" fonts (also type 1, and based on the `T1` encoding) instead usually produces good results with few significant differences in appearance.
according to the documentation for the `aecompl` package, the `ae` fonts are "virtual" fonts built mostly from the (type 1) `cm` fonts, except for a few characters that don't exist in the `cm` complement. so, in most cases, the results should be equivalent to that from using `cm` fonts directly.
however, given that the latin modern fonts are based on much the same model as `cm`, with the added advantage of having precomposed accented letters, i see no reason not to specify `\usepackage{lmodern}`. i know of no conflicts with the ams document classes.